mfi 


LIBRARY 

OF   THE 

University    of    North    (Carolina 

Endowed  by  the  Dialectic  and  Philanthropic- 
Societies. 


Call  No. 


UNIVERSITY  OF  NIC.  AT  CHAPEL  HILL 


00010361636 


:..-,..  s« 


^-^WjAA^4jZi 


U 


OF 


QUANTITATIVE  CHEMICAL  ANALYSIS 


FOR    THE    USE   OF  STUDENTS. 


BY 


FREDERICK  A.  CAIRNS,  A.  M.; 

INSTRUCTOR  IN  ANALYTICAL  CHEMISTRY   SCHOOL   OF 
MINES,    COLUMBIA  COLLEGE. 


NEW    EDITION.    REVISED    AND    EDITED    BY 
E.  WALLBE,  Fh.D., 

INSTRUCTOR  IN  ANALYTICAL   CHEMISTRY  IN   SCHOOL   OF   MINES. 


Qb/Q/ 


&A0  , 


NEW    YORK 

HENRY  HOLT  AND  CC 

1888 


*Af£i. 


Copyright,  1830, 
By  MART  SNOWDEN   CAIKN8. 


TO 


PROFESSOR    CHARLES    F.    CHANDLER, 

THE     FRIEND,     TEACHER,     AND     CO-LABORER     OF     THE 

AUTHOR,  THIS  BOOK  IS,  IN  ACCORDANCE 

WITH     THE     AUTHOR'S 

WISHES. 

DEDICATE!}. 


^0 

•Os. 


NOTE    BY    THE    EDITOR. 


Mr.  F.  A.  Cairns,  the  author  of  this  work,  died  sud- 
denly while  engaged  in  preparing  the  first  edition  for  the 
press. 

The  undersigned  completed  what  was  found  to  be 
necessary,  and  the  work  was  published. 

After  using  it  in  class  room  and  laboratory  for  a  year, 
it  has  been  deemed  advisable  to  prepare  and  issue  a  new 
edition  in  which  a  few  typographical  errors  have  been 
corrected  and  some  notes  of  an  explanatory  nature  added. 
In  a  few  cases  it  has  also  been  found  preferable  to  modify 
the  phraseology  employed,  and  a  new  chapter  has  been 
added  on  the  testing  of  illuminating  gas. 

It  is  to  be  hoped  that  the  changes  made  will  meet  with 
the  approval  of  those  making  use  of  the  book,  and  that 
the  conscientious  labors  of  the  author  will  still  have  the 
cordial  appreciation  of  workers  in  this  branch  of  chemistry. 

E.  Waller. 

« 


• 


AUTHOR'S   PREFACE. 


This  little  manual  is  designed  to  assist  beginners  in  the  practice 
of  quantitative  analytical  chemistry. 

The  aim  is,  by  explaining  some  of  the  more  serious  obstacles  to 
successful  analysis,  to  teach  thoughtfulness  and  caution,  and  by 
giving  very  explicit  directions  in  the  earlier  part  of  the  course,  to 
induce  habits  of  precision,  and  impart  a  sufficient  amount  of 
knowledge  of  chemical  manipulation  to  enable  the  student  to  pro- 
ceed without  further  leading. 

The  system  adopted  is  to  teach  at  first  the  determination,  indi- 
vidually, of  the  constituents  of  compounds,  composed  of  elements 
which  will  afterward,  very  frequently,  be  found  variously  asso- 
ciated, particularly  in  mineral  analysis  ;  and  then  to  teach  the 
quantitative  separation  of  these  elements,  in  the  analysis  of  com- 
pounds containing  a  number  of  them  ;  advancing,  step  by  step, 
from  the  analysis  of  compounds  of  similar  character  to  the 
analysis  of  more  complicated  ones,  involving  a  knowledge  and 
application  of  what  has  preceded. 

In  addition  to  the  series  of  what  may  be  called  strictly  mineral, 
have  been  added  a  number  of  analyses  of  substances  of  an  organic 
character,  found  in  commerce,  which  will  give  the  student  an 
insight  into  the  work  which  will  probably  be  required  of  him  as  a 
practical  chemist. 

The  range  of  these  is  necessarily  restricted,  as  it  is  desired  to 
keep  the  work  within  the  limits  of  a  simple  hand-book. 

The  writer  has  avoided  giving  numerous  methods  of  analysis  of 
the  same  substance,  but  has  selected  those  which  he  knows  to  be 
good,  and  which  he  believes  to  be  the  best. 

The  instructor  is  expected  to  enlarge  upon  the  instructions 
given  here,  and  the  student  to  study  other  works  of  a  more 
elaborate  character.  Success  requires  knowledge  of  theoretical 
chemistry  and  quantitative  analysis. 


REFERENCES. 


The  references  are  to  : 
' '  Fres. ,  Qual.  Anal. " — 

Fresenius's  Manual  of  Qualitative  Analysis.     Translated  into  the  new 
system.     Edited  by  S.  W.  Johnson.     New  York  :  1875. 
u,Fres.,  Quant.  Anal.'''1 — 

Quantitative  Chemical  Analysis.     By  Dr.  C.  R.  Fresenius.     Edited  by 
S   W.  Johnson.     New  York  :  1871. 
'H.  Rose,  Quant.  Anal.'''' — 

Traite  Complet  de  Chimie  Analytique,  par  M.  Henri  Rose.     Edition 
Francaise  originate,  Analyse  Quantitative.     Paris  :  1862. 


TABLE    OE    CONTENTS. 


Chapter.  Pa0K: 

Introduction ■L 

I. — Barium  Chloride • ■  •  •     *■* 

II. — Magnesium  Sulphate. 17 

III.— Calcium  Carbonate. . . . . . 20 

IV. — Potassium  Alum . . 26 

Y. — Calcium  Fluoride 31 

VI. — Potassium  Iodide 34 

VII. — Potassium  Bromide 35 

VIII.— Hydro-Disodium  Phosphate 36 

IX. — Ammonio-Ferric  Sulphate,  or  Ammonia  Iron  Alum 40 

X.— Feldspar........ 49 

XI. — Limestone. ....... 59 

XH.r-Clay.... ........ ............  ..........................     G7 

XIII.— Manganese  Ore  ........ . 70 

XIV. — Partial  Analysis  of  Iron  Ore. 78 

XV. — Complete  Analysis  of  Iron  Ore.. 86 

XVI.— Slag. .. . 100 

XVII.— Cast-Iron,  Steel,  and  Wrought-Iron 102 

XVIII.— Zinc  Ore= ................. 123 

XIX.— Nickel  Ore ............ . ........................   ....  127 

XX.— Copper  Ore. .................*....  .v. ..................  136 

XXI.— German  Silver  ............. . . . .  s . . . . . ... . . . .............  140 

XXIL— Galena..............    ...........:................*..   ...  142 

XXIII.— Tin  Ore 145 

XXIV.— Bronze. .. . 147 

XXV.— Arsenic  Ore 149 

XXVI,— Antimony  Ore 152 

XXVII.—  Type  Metal 154 

XXVIII.— Refined  Lead 157 

XXIX.— White  Paint  Ground  in  Oil 167 

XXX.— Fresh  Water 173 

XXXI.—  Mineral  Water 184 

XXXII.— Superphosphate  of  Lime.. .197 

XXXIII.— Milk , ., 204 

XXXIV. — Acidimetry  and  Alkalimetry 207 

XXXV. — Commercial  Bicarbonate  of  Soda 215 


yiii  CONTENTS . 

Chapter  .  Page. 

XXXVL— Chlorimetry 218 

XXXVII.— Acetate  of  Lime 221 

XXXVIII.— Guano 223 

XXXIX.— Raw  Sugar 226 

XL. — Sugar  (Ultimate  Analysis) 231 

XLL— Turpentine  (Ultimate  Analysis) 233 

XLIL— Bone-Black .234 

XLIII.-Coal 238 

XLIV.— Petroleum 242 

XLV, — Examination  of  Illuminating  Gas. . .  245 

XLVI.  -Soap . . . .  252 

XL VII.—  Flour ...... 255 

TABLES. 

Comparison  of  French  and  U.  S.  Weights  and  Measures « 262 

Atomic  Weights 263 

Specific  Gravities  and  Degrees  Beaume.  . , .    264,  265 

Strength  of  Sulphuric  Acid 265 

"         "  Hydrochloric  Acid 265 

"        "  Nitric  Acid 267 

1  <  Tartaric  Acid 23S 

"  Citric  Acid 268 

"Acetic  Acid 269 

"         "'Ammonia 269 

"  Potash  Lye 270 

■«        "  Soda  Lye 270 

"         "  Sodium  Chloride  ... 271 

Si        "  Ammonium  Chloride 27 1 


INTRODUCTION". 


As  gravimetric  analysis  is  effected  by  separating,  one  by 
one,  the  different  constituents  from  a  solution  containing 
a  known  amount  of  the  substance  to  be  analyzed  by  adding 
other  substances,  called  reagents,  which  will  form  with  the 
constituents  to  be  determined  compounds  insoluble  in  the 
surrounding  fluid,  care  must  be  taken  not  to  use  excessive 
quantities  of  these  reagents. 

Take,  as  an  illustration,  the  analysis  of  limestone.  After 
decomposing  the  stone  and  separating  the  silica,  which  is 
done  in  acid  solution,  the  solution  is  made  alkaline  with 
ammonia,  by  which  means  the  ferric  and  aluminic  hy- 
drates, being  insoluble  in  ammonia,  are  precipitated ;  the 
lime  is  then  precipitated,  by  the  addition  of  ammonium 
oxalate,  m  calcium  oxalate,  a  compound  insoluble  in  am- 
monia ;  the  magnesia  is  then  precipitated  from  the  residual 
fluid  as  magnesium  ammonium  phosphate  (by  the  addition 
of  sodium  phosphate),  a  compound  insoluble  in  ammonia. 

This  is  the  outline  of  the  method  of  analysis.  Suppose 
an  excessive  quantity  of  hydrochloric  acid  to  have  been 
used  in  the  flrst  instance,  a  large  quantity  of  ammonia 
would  be  required  to  precipitate  the  iron  and  alumina,  and 
consequently  a  large  quantity  of  ammonium  chloride  formed 
in  the  solution.  If,  in  addition  to  this,  an  unnecessary 
quantity  of  ammonium  oxalate  were  used,  it  would  be 
found  impossible  to  complete  the  analysis   successfully 


M  INTRODUCTION. 

without  danger  of  loss  and  great  waste  of  time  and  labor. 
The  danger  of  loss  al ways  accompanies  prolonged  operations 
in  chemistry  ;  the  waste  of  time  would  be  consequent  upon 
the  necessity  of  evaporating  to  dryness  to  expel  the  large 
amount  of  ammonium  chloride,  in  the  presence  of  which 
the  magnesium  could  not  be  completely  precipitated  (an 
operation  involving  considerable  loss  of  time  and  possibly 
of  substance).  Finally,  after  all  this  waste  of  time  and 
labor,  the  presence  of  other  salts,  not  volatilized  by  heat, 
would  render  it  impossible  to  concentrate  the  fluid  to  the 
proper  point  for  the  thorough  precipitation  of  the  mag- 
nesium as  phosphate,  it  being  somewhat  soluble  in  large 
amounts  of  fluid.  Such  difficulties  as  these  can  in  nearly 
all  cases  be  avoided  by  using  no  more  of  a  solvent  (acid  or 
alkaline)  than  is  necessary,  and  no  more  of  a  precipitant 
than  is  required  to  effect  complete  precipitation,  or,  in 
other  words,  by  avoiding  excessive  use  of  reagents  in  all 
cases. 

A  knowledge  of  the  use  of  solvents  can  be  attained  by 
studying  the  solubility  of  substances,  and  a  knowledge  of 
the  amount  of  reagents  to  be  used  by  simple  stoichiomet- 
rical  calculations.  The  student  should  bear  in  mind  that 
water  is  also  a  reagent,  and  that  excessive  use  of  it  is  to  be 
condemned.  At  the  end  of  this  chapter  will  be  found  a 
table  giving  the  amount  of  the  different  elements,  etc., 
precipitated  by  1  c.  c.  of  a  solution  of  each  of  the  reagents 
most  commonly  used. 

Before  beginning  an  analysis  of  any  complexity,  a  plan 
should  be  adopted  and  well  studied.  In  many  cases,  tabular 
schemes  will  be  found  very  useful,  as  they  enable  the 
chemist  to  see  at  a  glance  the  relative  bearing  of  each  part 
of  an  analysis,  and  refresh  the  memory  without  loss  of  time. 

MEASURING. 

This  requires  vessels  of  various  kinds,  the  capacity  of 
which  is  known,  such  as  flasks,  pipettes,  burettes,  etc. 


•      MEASURING.  3 

Flasks. — Of  these  it  is  well  to  have  a  series  which  will 
deliver  respectively  50  c.  a,  100  c.  c,  150  c.  c,  200  c.  a, 
250  c.  c,  300  c.  c.j  500  c.  c,  and  1000  c.  c.  In  most  cases, 
it  is  not  of  so  mnch  importance  that  they  should  be  ab- 
solutely accurate  as  to  capacity,  as  that  they  should  bear 
an  accurate  relationship  to  each  other,  as  otherwise  it  will 
be  impossible  to  divide  solutions  correctly,  a  matter  of  the 
greatest  importance  in  quantitative  analysis.  If  it  is  desired 
to  standardize  a  flask  with  great  precision,  it  can  be  done 
by  counterpoisirg  it  on  a  balance  with  any  kind  of  weight 
that  is  convenient,  adding  weights  to  those  on  the  balance 
to  an  amount  corresponding  to  the  capacity  of  the  flask, 
adding  the  proper  amount  of  water,  and  marking  the  neck 
of  the  flask.  As  an  illustration,  we  will  suppose  that  it  is 
desired  to  prepare  a  50  c.  c.  flask.  Select  a  flask  with  a 
narrow  neck,  in  which  the  water  will  rise  about  half-way, 
upon  introducing  about  50  c.  c.  of  it ;  dry  the  flask  thor- 
oughly, inside  and  out,  place  it  upon  the  pan  of  a  balance, 
counterpoise  it  with  any  convenient  weight,  add  to  the 
weight  49.9405  gms.,  and  introduce  into  the  flask  distilled 
water  of  16°  C,  until  perfect  equilibrium  is  produced 
(after  drying  the  neck  of  the  flask  above  the  water-line). 
Then  mark  the  neck  of  the  flask,  which  must  stand  perfectly 
level,  where  it  is  intersected  by  the  horizontal  plane  coin- 
ciding with  the  bottom  of  the  meniscus.  This  mark  is  what 
is  called  the  ' '  holding  "  or  "  containing ' '  mark.  Of  course, 
when  the  contents  of  the  flask  are  poured  out,  some  of  the 
fluid  will  adhere  to  the  sides,  and  it  will  fail  to  deliver  50 
c.  c.  It  becomes  necessary,  therefore,  to  establish  a  point 
to  which  the  flask  must  be  filled  to  enable  it  to  deliver  50 
c.  c.  To  do  this,  fill  the  flask  with  water,  empty  it,  counter- 
poise it  as  before,  together  with  the  fluid  adhering  to  the 
inside,  being  careful  that  the  outside  is  dry,  replace  the 
weights  amounting  to  49.9405  gms.,  introduce  distilled 
water  of  16°  C.  until  equilibrium  is  restored  as  before, 
and  mark  the  neck  of  the  flask  where  it  is  intersected 
by  the  horizontal  plane  tangent  to  the  bottom    of  the 


4  INTRODUCTION. 

meniscus.     This  mark  is  what  is  called  the  "delivery'* 
mark. 

In  this  way,  all  the  flasks  required  can  be  prepared  with 
great  accuracy.  If,  however,  an  accurately  measured  flask 
is  at  hand,  another  of  twice  or  thrice  the  capacity  can 
readily  be  prepared  by  filling  the  smaller  flask  to  the  deliv- 
ery mark  with  water  of  16°  C,  emptying  it  into  the  larger 
flask,  previously  dried,  repeating  until  the  desired  volume 
is  reached,  and  marking  upon  the  neck  of  the  flask  the 
holding  point.  By  repeating  the  operation  upon  the  wet 
flask,  the  delivery  mark  can  be  established. 

Flasks  can  also  be  prepared  with  great  ease  by  means 
of  a  pipette  the  capacity  of  which  is  known.  If,  for  instance, 
a,  pipette  which  is  known  to  deliver  50  c.  c.  is  at  hand, 
all  that  is  necessary  to  prepare  a  200  c.  c.  flask  is  to  dry 
it,  run  into  it  4  pipette-fulls  of  water  of  16°  C,  and  mark 
the  proper  point  on  the  neck  as  the  holding  mark ;  and 
determine  the  delivery  mark  by  repeating  on  the  wet  flask. 

Pipettes. — These  can  usually  be  purchased  cheaply,  so 
that  ordinarily  there  is  no  occasion  to  make  or  graduate 
them.  Their  accuracy  should,  however,  always  be  verified. 
This  is  commonly  done  by  filling  them  up  to  the  proper 
mark  with  water  of  16°  C,  running  this  water  into  a 
weighed  flask,  and  weighing  the  amount  delivered.  This 
should  be  nearly  the  same  number  of  grammes  as  the 
pipette  is  supposed  to  contain  in  cubic  centimetres,  a  slight 
difference  being  made  for  the  expansion  of  water  between 
0  and  16°  C.  One  cubic  centimetre#  of  water  at  16°  C. 
weighs  0.9988  gms. 

A  pipette  must  always  be  filled  by  suction  to  above  the 
mark,  with  the  liquid  to  be  measured ;  then,  by  closing  the 
top  with  the  dry  finger,  the  liquid  may  be  allowed  to  run 
slowly  out,  until  the  lower  part  of  the  meniscus  is  at  the 
line.  It  will  then  (if  correct)  deliver  the  number  of  c.  c. 
marked  upon  it.  Pipettes  being  used  for  delivery  only, 
have  no  holding  mark,  as  with  flasks.  In  running  the 
liquid  out  of  the  pipette,  touch  the  tip  lightly  against  the 


WEIGHING.  O 

side  of  the  vessel  into  which  it  is  delivering,  until  no  more 
runs  out.  Never  blow  out  the  last  drop,  since  that  ren- 
ders the  measurement  inaccurate. 

If  a  burette  is  taken,  the  accuracy  of  which  has  been 
verified  by  weighing  the  amounts  delivered,  as  referred  to 
above,  the  accuracy  of  any  number  of  pipettes  may  be 
readily  tested,  by  first  filling  them  with  water,  running  it 
out  so  as  to  leave  the  same  amount  adhering  to  the  glass 
as  when  in  use,  and  then  closing  the  tip  with  the  finger, 
and  running  in  water  of  16°  C.  from  the  burette.  For 
this  work,  the  burette  should  be  provided  with  a  fine- 
pointed  delivery -jet. 

The  same  method  will  serve  for  graduation,  if  that  is 
necessary.  (See  Thorpe's  "  Quant.  Anal."  pp.  112  et 
seq.)  Students  should  also  have  a  few  small  test  glasses 
holding  from  10  to  15  c.  c,  and  graduated  to  c.  c.  These 
will  be  found  more  convenient  for  controlling  the  use  of 
reagents  than  pipettes,  and  for  most  purposes  are  suf- 
ficiently accurate. 

For  measuring  of  gases,  read  Fresenius,  who  extracts 
from  the  best  authorities,  such  as  Bunsen,  Eegnault,  and 
others. 

WEIGHING. 

As  quantitative  analysis  requires,  in  addition  to  the  sep- 
aration of  the  constituents  of  a  substance,  the  determina- 
tion of  their  relative  quantity,  accurate  weighing  is  abso- 
lutely necessary.  A  good  balance  is,  of  course,  essential. 
For  discussions  of  the  principles  of  the  balance,  the  student 
is  referred  to  such  works  as  that  of  Fresenius,  as  space  will 
not  allow  their  being  introduced  here.  Rules  for  weigh- 
ing are  all  that  are  admissible.  Those  given  by  Fresenius 
are  introduced  here. 

1.  The  safest  and  most  expeditious  way  of  ascertaining 
the  exact  weight  of  a  substance  is  to  avoid  trying  weights 
at  random ;  instead  of  this,  a  strictly  systematic  course 
ought  to  be  pursued  in  counterpoising  substances  on  the 


6  INTRODUCTION. 

balance.  Suppose,  for  instance,  we  want  to  weigh,  a  cru- 
cible, the  weight  of  which  subsequently  turns  out  to  be 
6.627  gms.  ;  we  place  10  gms.  on  the  other  scale  against 
it,  and  we  find  this  too  much  ;  we  place  the  weight  next 
in  succession,  i.  e.,  5  gms.,  and  find  this  too  little ; 
next  7,  too  much ;  6,  too  little  ;  6.5,  too  little  ;  6.7,  too 
much  ;  6.6,  too  little  ;  6.65,  too  much  ;  6.62,  too  little ;  6.63, 
too  much;  6.625,  too  little  ;  6.627,  right. 

I  have  selected  here,  for  the  sake  of  illustration,  a  most 
complicated  case  ;  but  I  can  assure  the  student  of  quanti- 
tative analysis  that  this  systematic  way  of  laying  on  the 
weights  will,  in  most  instances,  lead  to  the  desired  end  in 
half  the  time  required  when  weights  are  tried  at  random. 
After  a  little  practice,  a  few  minutes  will  suffice  to  ascer- 
tain the  weight  of  a  substance  to  within  the  tenth  of  a 
milligramme,  provided  the  balance  does  not  oscillate  too 
slowly. 

2.  The  milligrammes  and  fractions  of  milligrammes  are 
determined  by  a  centigramme  rider  (to  be  placed  on  or  be- 
tween the  divisions  on  the  beam)  far  more  expeditiously 
and  conveniently  than  by  the  use  of  the  weights  them- 
selves, and  at  the  same  time  with  equal  accuracy. 

3.  Particular  care  and  attention  should  be  bestowed  on 
entering  the  weights  in  the  book.  The  best  way  is  to 
write  down  the  weights  first  by  reference  to  the  blanks  or 
gaps  in  the  weight-box,  and  to  control  the  entry  subse- 
quently by  removing  the  weights  from  the  scale,  and  re- 
placing them  in  their  respective  compartments  in  the  box. 
The  student  should,  from  the  commencement,  make  it  a 
rule  to  enter  the  number  to  be  deducted  in  the  lower  line  ; 
thus,  in  the  upper  line,  the  weight  of  the  crucible  +  ^ne 
substance ;  in  the  lower  line,  the  weight  of  the  empty  cru- 
cible. 

4.  The  balance  ought  to  be  arrested  every  time  any 
change  is  contemplated,  such,  as  removing  weights,  substi- 
tuting one  weight  for  another,  etc.,  etc.,  or  it  will  soon  be 
spoiled. 


WEIGHING.  7 

5.  Substances  (except,  perhaps,  pieces  of  metal,  or  some 
other  bodies  of  the  kind)  must  never  be  placed  directly 
upon  the  scales,  but  oYight  to  be  weighed  in  appropriate 
vessels  of  platinum,  silver,  glass,  porcelain,  etc.,  never  on 
paper  or  card,  since  these,  being  liable  to  attract  moisture, 
are  apt  to  alter  in  weight.  The  most  common  method  is 
to  weigh,  in  the  first  instance,  the  vessel  by  itself,  and  to 
introduce  subsequently  the  substance  into  it ;  to  weigh 
again,  and  subtract  the  former  weight  from  the  latter.  In 
many  instances,  and  more  especially  where  several  portions 
of  the  same  substance  are  to  be  weighed,  the  united  weight 
of  the  vessel  and  of  its  contents  is  first  ascertained  ;  a 
portion  of  the  contents  is  then  shaken  out,  and  the  vessel 
weighed  again,  the  loss  of  weight  expresses  the  amount  of 
the  portion  taken  out  of  the  vessel.  ' 

6.  Substances  liable,  to  attract  moisture  from  the  air 
must  be  weighed  invariably  in  closed  vessels  (in  covered 
crucibles,  for  instance,  or  between  two  watch-glasses,  or 
in  a  closed  glass  tube) ;  fluids  are  to  be  weighed  in  small 
bottles  with  glass  stoppers. 

7.  A  vessel  ought  never  to  be  weighed  while  warm, 
since  it  will  in  that  case  invariably  weigh  lighter  than  it 
really  is.  This  is  owing  to  two  circumstances.  In  the  first 
place,  every  body  condenses  upon  its  surface  a  certain 
amount  of  air  and  moisture,  the  quantity  of  which  depends 
upon  the  temperature  and  hygroscopic  state  of  air,  and 
likewise  on  its  own  temperature.  Now,  suppose  a  crucible 
has  been  weighed  cold  at  the  commencement  of  the  oper- 
ation, and  is  subsequently  weighed  again  while  hot,  together 
with  the  substance  it  contains,  and  the  weight  of  which  we 
wish  to  determine.  If  we  subtract,  for  this  purpose,  the 
weight  of  the  cold  crucible,  ascertained  in  the  former 
instance,  from  the  weight  found  in  the  latter,  we  shall 
subtract  too  much,  and  consequently  we  shall  set  down 
less  than  the  real  weight  of  the  substance.  In  the  second, 
place,  bodies  at  a  high  temperature  are  constantly  com- 
municating heat  to  the  air  immediately  around  them  ;  the 


8  INTRODUCTION. 

heated  air  expands  and  ascends,  and  the  denser  and  colder 
air,  flowing  toward  the  space  which  the  former  leaves,  pro- 
duces a  current  which  tends  to  raise  the  scale-pan,  making 
it  thus  appear  lighter  than  it  really  is. 


FILTERING  AND   BEAKEES,    ETC.,    WASHING-. 

Lipped  beakers  are  always  preferable.  In  pouring  from 
a  beaker,  the  stream  should  be  always  poured  against  a 
glass  rod.  No  grease  is  required  on  the  under  side  of  the 
lip,  if  it  is  properly  formed.  The  under  side  of  the  lip 
should  always  be  dry.  Rubbers  on  the  rods  should  only 
be  used  to  clean  vessels.  In  filtering,  the  rods  should 
have  no  rubbers  on  them,  as  it  may  introduce  organic 
matter  into  the  solutions,  which  may  cause  error  in  the 
work. 

When  a  vessel  holding  several  litres  is  to  be  heated,  as 
it  may  be  fractured  by  the  great  weight  of  fluid,  if  the 
bottom  rests  unevenly  upon  its  support  in  heating,  sand 
may  be  used  as  a  support.  In  other  cases,  the  use  of  sand 
is  objectionable.  It  requires  a  longer  time  to  heat  a  vessel 
standing  upon  sand,  and  the  sand  is  very  liable  to  adhere 
to  the  bottom  of  the  vessel,  and  from  it  drop  into  the 
analysis. 

In  filtering,  the  filter  should  always  be  accurately  fitted 
to  the  funnel,  and  the  funnel  adapted  to  the  size  of  the 
filter,  always  using  the  smallest  filter  that  will  allow  a 
proper  washing  of  the  contents.  The  larger  the  filter,  the 
more  washing  it  requires,  and  the  greater  the  liability  to 
error  in  allowing  for  the  weight  of  the  ash. 

Corrugated  filters  should  never  be  used  in  quantitative 
work,  where  the  precipitate  is  to  be  weighed,  as  it  is  very 
difficult  to  wash  them  properly,  and  it  is  very  difficult  to 
remove  the  precipitate  from  them,  which  is  often  neces- 
sary. 

In  washing,  allow  all  the  solution  to  run  through  the 


FILTERING  AND   BEAKERS,    ETC.,    WASHING.  9 

filter,  before  adding  any  water,  then  fill  up  the  filter  with 
water,  and  allow  that  to  run  through  before  adding  more. 
By  this  means,  excessive  quantities  of  wash-water  may  be 
avoided.  In  washing  by  decantation,  which  is  necessary 
with  some  precipitates,  the  same  principle  is  used.  Allow 
the  precipitate  to  settle,  decant  as  closely  as  possible, 
pouring  the  liquid  through  the  filter,  add  water,  stir  well, 
let  settle,  and  decant  again  closely  before  adding  more 

wash-water. 

Crucibles  and  Ignition. — Crucibles  should  always  have 
covers  and  be  cooled  and  weighed  with  them  on,  to  avoid 
loss  of  substance  and  to  exclude  dust,  etc. 

Previous  to  ignition,  the  filters  and  contents  must  be 
thoroughly  dried;  on  ignition,  the  paper t must  be  thor- 
oughly consumed,  so  that  no  carbon  remains.  Heat  gently 
at  first,  so  as  to  carbonize  the  filter  without  flame,  and 
afterward  intensely.  The  destruction  of  the  filter-paper 
is  most  readily  effected  by  tilting  the  crucible,  and  finish- 
ing the  ignition  with  the  cover  off.  It  is  best  to  remove 
,the  contents  from  the  filter  so  far  as  possible,  before  ig- 
niting. In  many  cases,  the  removal  of  any  of  the  contents 
is  impossible.  In  such  cases,  roll  up  the  filter  and  con- 
tents, and  burn  both  together.  If  the  substance  is  one 
which  may  be  reduced  by  the  carbon  of  the  filter-paper 
(as  lead  sulphate,  etc.),  moisten  with  a  little  concentrated 
nitric  acid  or  strong  solution  of  ammonium  nitrate  before 
igniting.  Where  the  most  of  the  precipitate  can  be  re- 
moved from  the  filter  without  loss,  it  is  better  to  do  so, 
and  reserve  the  precipitate  in  a  watch-glass  or  convex 
cover,  until  the  filter-paper  has  been  consumed. 

Where  substances  readily  reducible  are  to  be  weighed, 
which  might  form  a  fusible  alloy  with  platinum  (lead 
sulphate,  silver  chloride,  etc.),  porcelain  crucibles  should 
be  used. 

Note-Books. — Notes  should  never  be  kept  on  loose  scraps 
of  paper,  but  in  regular  note-books,  of  a  size  sufficient  to 
allow  of  keeping  a  clear  record  of  the  work,  for  reference 


10  INTEODTJCTION. 

at  any  time.  It  is  convenient  to  get  in  the  habit  of  setting 
down  the  weight  of  the  vessel  in  which  a  substance  is  to  be 
weighed,  in  the  lower  line  of  the  two  intended  for  that 
purpose.  In  the  case  given  below,  the  glass  for  the  iron 
wire  and  the  crucible  for  the  precipitate  are  always 
weighed  first,  but  the  weight  is  entered  on  the  lower  line 
of  the  two,  for  convenience  in  subtracting. 

As  an  illustration  of  a  clear  and  convenient  form  of 
keeping  a  note-book,  an  example  is  given.  The  analysis 
is  supposed  to  be  the  determination  of  iron  in  iron  wire  : 

Wt.  glass  -1-  Fe  wire 6.0765 

"    5.3000 

Fe  wire  taken 0.7765 

Wt.  Crucible  +  ignited  ppt.,  etc 25.5170 

24.4059 

ppt.  +  ash 1.1121 

"  filter-ash 0.0031 

"  ignited  ppt 1.1090 

Calculation : 

1.1090  X  |H  =  0.7763  Fe 
160 

0.7763  X  -^  =  99.97  per  cent  Fe, 
0.7/65 


JVIAKIISTG  UP  EEAGENTS. 

In  making  up  reagents,  pure  materials  and  distilled  water 
should  be  used.  In  the  table  below,  where  salts  are  men- 
tioned, the  crystallized  salts  (containing  water  of  crystal- 
lization) are  meant.  Salts  obtained  from  dealers,  and 
labelled  "  chemically  pure,"  are  seldom  absolutely  so,  and 
often  afford  a  sediment  when  their  solutions  are  allowed 
to  stand.  Tests  should  always  be  made  for  such  impurities 
as  may  interfere  with  the  work.    In  some  cases,  the  amount 


MAKING   UP   REAGENTS. 


11 


of  impurity  may  have  to  be  determined,  and  an  allowance 
made  for  it  in  the  work. 


Reagent. 

Barium  Chloride 

Hydro  d  i  s  o  d  i  c 
Phosphate 

Ammonium  Ox- 
alate  

Argentic  Nitrate 


Proportions  to  be  used. 
1  gm.  salt  10  c.  c.  water 

"     "      "     10  c.  c.       " 


1  c.  c.  of  solution 
ivill  precipitate  : 
0.0327  gm.  S03 


"     "       "    24  c.  c. 
"     "      "     20  c.  c.       " 
Sulphuric  Acid..    1  gm.  cone.  (gr.  1.84)  5  c.  c.  " 
11  "  1  c.  c.     "  "        5  c.  c.  " 


0.0112 

0.0145 
0.0104 
0.2522 
0.4291 


Platinic 
ide. 


Chlor- 


[  1  gm.  metal  dissolved  in  aqua  regia,  1  0.0390 

-(  evaporated  to  dryness  and  dissolved  }  0.0480 

in  1  c.  c.  HC1  +  9  c.  c.  water.  0.0750 


Magnesia  niix- 
ture,  v i  d  . 
Fres.  Quant 
§  62..  p.  89. 

3iolybdate  sohi- 
t  i  o  n .  v  i  d . 
Fres.  Qual. 

79 . 


1  gm.  MgS04  (salt),  1  gm.   NH4C1 
(salt),  4  c.  c.  ammonia,  8  c.  c.  water. 


1  gm.   Mo03  dissolved  in  4  c.  c.  am- 


monia, poured  into  15 
(gr.  1.2). 


0.0240 


0.0013 


CaO 
CI 
Ba 
Ba 

K 

KC1 


P.O. 


P*0B 


c.  HNCX 

§  55,  p.  72.  [ 

Ammonium  Carbonate,  1  gm.  salt,  1  c.  c.  ammonia. 

4  c.  c.  water. 
Sodium  Carbonate,  2.7  gm.  salt,  5  c.  c.  water. 

(Saturated  solution.) 
Ammonia,  gr.  0.96.* 
Hydrochloric  Acid,  gr.  1.12, 
Nitric  Acid,  gr.  1.2. 

*  The  strongest  concentrated  ammonia  has  a  gr .  of  0.880.     This,  diluted  with 
two  volumes  of  water,  will  have  a  gravity  of  0.96. 


CHAPTEE  I. 

BAEIUM   CHLOEIDE. 

BaCI2.2R20. 
The  composition  of  crystallized  baiiiun  cliloride  is : 

Ba 56.147  per  cent. 

CI , 29.099    "       " 

H20 -;'.. :./....    14.754    "       " 

100.000 

Pulverize  8  or  10  gms.,  and  keep  the  powder  in  a  corked 
tube  or  bottle.  For  the  determination  of  the  barium, 
dissolve  1  gm.  in  100  c.  c.  warm  water,  containing  a  few 
drops  of  hydrochloric  acid.  Heat  to  boiling,  and  add  2 
c.  c.  dilute  sulphuric  acid,  prepared  by  adding  1  part  by 
volume  of  strong  acid  to  5  parts  by  volume  of  water. 
Continue  boiling  for  1  minute.  Then  remove  the  heat, 
and  allow  the  precipitate  of  barium  sulphate  to  settle 
completely. 

To  determine  whether  or  not  a  sufficient  quantity  of  Sul- 
phuric acid  has  been  added,  place  2  or  3  drops  of  the  clear 
supernatant  fluid  on  a  watch-glass,  and  add  a  drop  of 
barium  chloride  solution.  If,  upon  the  addition  of  the 
barium  chloride,  the  fluid  becomes  turbid,  with  a  precipi- 
tate of  barium  sulphate,  there  is  evidently  a  sufficient 
quantity  of  sulphuric  acid  present  to  precipitate  all  the 
barium  in  the  solution.  Should  no  turbidity  appear  after 
adding  the  barium  chloride  to  the  solution  on  the  watch- 
glass,  add  1  c.  c.  more  of  the  dilute  sulphuric  acid  to  the 
main  solution,  boil,  and  test  a  few  drops  of  the  clear  fluid, 
as  before.  Eepeat  the  testing  and  addition  of  acid  until 
the  fluid  evidently  contains  an  excess.  When  the  pre- 
cipitation is  complete,  decant  the  clear  fluid  on  a  filter, 
without  disturbing  the  precipitate,  pour  100  c.  c.  boiling 
water  on  the  precipitate,  stir  well  with  a  glass  rod,  allow 


CHL0KLNE.  13 

the  precipitate  to  settle,  and  decant  as  before.  Repeat  this 
washing  by  decantation  several  times.  Then,  transfer  the 
precipitate  to  the  filter,  and  wash  with  hot  water  until  the 
wash- water  does  not  become  turbid  when  either  barium 
chloride  or  silver  nitrate  is  added  to  it.  After  filtering 
out  the  barium  sulphate  and  washing  by  decantation,  and 
before  transferring  the  precipitate  to  the  filter,  substitute 
a  clean  empty  beaker  for  the  one  containing  the  filtrate, 
in  order  that  an  unnecessary  amount  of  re-filtering  may  be 
avoided,  should  the  precipitate  of  barium  sulphate  run 
through  the  filter,  which  sometimes  happens  when  the 
filter-paper  is  very  thin.  Dry  the  precipitate  on  the  filter, 
and  when  it  is  dry  brush  it  from  the  filter  into  a  clock- 
glass  or  small  dish  as  completely  as  possible ;  burn  the 
filter  in  a  weighed  crucible,  keeping  the  crucible  covered 
until  the  paper  is  thoroughly  charred.  After  this,  remove 
the  cover  and  continue  to  heat  until  the  carbon  of  the 
paper  is  completely  consumed  and  only  white  ash  left. 
Then  transfer  the  precipitate  from  the  clock-glass  to  the 
crucible,  ignite  thoroughly,  cool  in  a  desiccator,  and  weigh. 
The  weight  will  be  that  of  the  crucible,  filter-ash,  and  pre- 
cipitate of  barium  sulphate.  Deduct  the  known  weight 
of  the  crucible  and  filter-ash,  and  from  the  remainder, 
which  will  be  the  weight  of  the  barium  sulphate,  calculate 
the  per  cent  of  barium.  ; 

The  combustion  of  the  filter  can  be  hastened  by  pressing 
it  against  the  side  of  the  crucible,  while  burning,  with  a 
clean  glass  rod. 

If  the  barium  sulphate  be  not  completely  removed  from 
the  filter  before  burning  it,  a  little  may  possibly  be  re- 
duced to  barium  sulphide  by  the  carbon  of  the  filter. 
This  danger  may  be  avoided  by  moistening  the  filter-ash 
with  two  or  three  drops  of  sulphuric  acid,  drying,  and  ig- 
niting again,  before  transferring  the  precipitate  to  the 
crucible. 

For  the  determination  of  the  chlorine,  dissolve  0.500  gm. 
of  the  pulverized  barium  chloride  in  a  small  conical  part- 


14  BARIUM   CHLOEIDE. 

ing-flask,  or  matrass,  sucli  as  is  used  in  the  assay  of  gold. 
Fill  the  flask  about  half  full  with  warm  water — warm  to 
about  60°  C.j  and  add  16  c.  c.  of  a  solution  of  silver  nitrate? 
prepared  by  dissolving  1  part  by  weight  of  pure  silver 
nitrate  in  20  parts  of  water,  add  1  c.  c.  of  nitric  acid,  cork 
the  flask,  and  shake  well.  When  the  precipitate  has  set- 
tled, add  1  c.  c.  more  of  the  solution  of  silver  nitrate,  and 
notice  carefully  whether  or  not  it  causes  another  precip- 
itate. If  it  should  do  so,  shake,  and  allow  the  silver  chlor- 
ide to  settle,  add  another  c.  c.  of  the  silver  nitrate  solu- 
tion, and  proceed  in  the  same  way  until  no  new  precip- 
itate forms,  and  the  solution  "brightens,"  as  it  is  termed ; 
that  is,  looks  perfectly  clear.  Heat  to  60°  C.  Allow  the 
precipitate  to  settle  completely,  till  the  flask  with  warm 
water,  place  over  the  mouth  a  weighed  porcelain  crucible 
of  a  proper  size  to  allow  the  mouth  of  the  flask  to  touch 
the  bottom  of  it,  and  invert  it  quickly.  Hang  the  flask 
by  means  of  a  wire  triangle  in  a  ring  of  an  ordinary  ring- 
stand,  over  an  evaporating  dish  sufficiently  large  to  hold 
more  than  the  contents  of  the  flask.  Lower  the  ring  until 
the  crucible  stands  on  the  bottom  of  the  dish,  the  crucible 
being  all  the  time  pressed  iirmly  against  the  mouth  of  the 
flask.  Fill  the  crucible  with  water  and  gently  raise  the 
ring,  adding  water  while  doing  so,  until  the  mouth  of  the 
flask  is  so  slightly  submerged  that  a  watch-glass,  a  trifle 
larger  than  the  crucible,  can  be  slipped  under  it.  Do  not 
place  the  watch-glass  under  the  mouth  of  the  flask  at  first, 
but  allow  the  whole  to  stand  for  some  hours,  protected  as 
far  as  possible  from  the  light. 

The  precipitate  will  usually  settle  entirely  from  the 
flask  into  the  crucible  ;  should  any  particles  adhere  to  the 
sides  of  the  flask,  slight  tapping  will  cause  them  to  de- 
scend. After  all  the  precipitate  has  settled  into  the  cru- 
cible, slip  the  watch-glass  under  the  mouth  of  the  flask, 
and,  while  holding  it  firmly  against  it  with  one  hand, 
remove  the  crucible  containing  the  silver  chloride  with 
the  other  ;  allow  the  fluid  in  the  flask  to  run  out  slowly 


CHLORINE.  15 

into  the  dish  by  moving  the  watch-glass  gently  with  a 
rocking  motion.  Now  pour  the  fluid  in  the  crucible  care- 
fully into  another  vessel,  or,  for  greater  security,  on  a  filter. 
Wash  repeatedly  with  hot  water,  containing  a  little  nitric 
acid,  decanting  on  the  filter  as  before,  until  the  washings 
do  not  become  turbid  upon  the  addition  of  hydrochloric 
acid.  In  testing,  use  only  a  few  drops  at  a  time,  in  a  very 
slender  test-tube.  Remove  the  last  drops  of  fluid  from 
the  crucible  with  a  strip  of  bibulous  paper,  being  careful 
not  to  take  up  any  silver  chloride  ;  should  any  particles 
adhere,  they  can  be  washed  back  into  the  crucible,  and  the 
fluid  removed  as  before.  By  a  little  care  and  dexterity,  all 
but  a  very  small  quantity  of  fluid  can,  in  this  way,  be  re- 
moved. Evaporate  ofl  what  remains  in  the  crucible,  and 
then  dry  it,  with  its  contents,  in  a  drying  chamber. 
When  all  visible  moisture  is  removed,  heat  over  a  low 
flame,  until  the  silver  chloride  begins  to  fuse  well  around 
the  edge  ;  cool  and  weigh.  Deduct  from  this  weight  the 
known  weight  of  the  crucible.  The  remainder  will  be  the 
weight  of  the  silver  chloride.  From  this,  calculate  the  per 
cent  of  chlorine.  The  silver  chloride  should  not  be  fused 
at  a  high  heat,  as  it  will  volatilize  some  of  it.  This  is  the 
best  method  of  determining  chlorine  gravimetrically,  where 
a  large  quantity  of  silver  chloride  is  to  be  handled. 

The  silver  chloride  can  be  precipitated  in  a  beaker  in- 
stead of  a  flask,  and  filtered  out.  Precipitate  in  the  same 
way  as  directed  above  ;  pour  the  clear  fluid  on  the  filter, 
wash  a  few  times  by  decantation  with  hot  water  acidu- 
lated with  nitric  acid,  transfer  the  precipitate  to  the  filter, 
and  wash  with  hot  water  acidulated  with  nitric  acid,  until 
the  washings  do  not  become  turbid  upon  the  addition  of 
hydrochloric  acid,  to  be  sure  that  the  excess  of  silver 
nitrate  is  washed  out.  Dry  the  precipitate  in  the  funnel 
in  an  air-bath.  When  the  precipitate  is  dry,  transfer  it  to 
a  clock-glass,  brushing  the  filter  as  clean  as  possible  with 
a  feather  ;  place  the  filter  in  a  weighed  porcelain  crucible, 
moisten  it  with  a  few  drops  of  nitric  acid,  and  burn  it 


16  BARIUM   CHLORIDE. 

until  all  carbon  is  consumed.  Let  the  crucible  cool  enough 
to  be  handled,  add  a  few  drops  of  nitric  acid,  and  warm, 
to  dissolve  the  metallic  silver  which  is  due  to  the  re- 
duction of  the  silver  chloride  by  the  carbon  of  the  filter. 
Then  add  a  few  drops  of  hydrochloric  acid  and  evaporate 
to  dryness.  Transfer  the  precipitate  from  the  clock-glass 
to  the  crucible,  fuse  as  directed  above,  cool  and  weigh. 
The  weight  will  be  that  of  the  crucible,  filter-ash  and  silver 
chloride.  Deduct  the  known  weight  of  the  crucible  and 
ash  of  filter ;  the  remainder  will  be  the  weight  of  the  silver 
chloride.     From  this,  calculate  the  per  cent  of  chlorine. 

Whichever  method  be  employed,  evaporate  the  filtrates 
and  washings  to  small  bulk,  after  adding  a  little  silver 
nitrate  and  nitric  acid.  Should  a  precipitate  of  silver 
chloride  be  formed,  treat  it  as  directed  above,  and  add  the 
per  cent  to  the  first. 

For  the  determination  of  water,  introduce  1  gm.  into  a 
weighed  crucible,  and  heat  very  gently  to  low  redness  ; 
cool  and  weigh.  Repeat  the  heating  and  weighing  until 
the  substance  ceases  to  diminish  in  weight.  Care  should 
be  taken  not  to  heat  too  highly,  as  by  doing  so  some 
chlorine  may  be  expelled. 

The  loss  of  weight  is  equivalent  to  the  water  ;  from  this, 
calculate  the  £>er  cent  of  water. 


CHAPTER  n. 

MAGNESIUM   SULPHATE. 

MgS0A.1H20. 
The  theoretical  composition  of  magnesium  sulphate  is  : 

MgO 16.26  per  cent, 

S03 > 3252    "       " 

H20 51.22    "       " 

100.00 

As  the  salt  is  slightly  efflorescent,  select  8  or  10  gms.  of 
crystals  that  have  not  ]ost  water  by  exposure,  pulverize 
them  quickly,  and  keep  the  powder  in  a  corked  tube  or 
bottle. 

For  the  determination  of  magnesia,  dissolve  about  1  gm. 
in  25  c.  c.  of  cold  water  in  a  small  beaker,  add  enough 
hydrochloric  acid  to  make  the  solution  distinctly  acid  to 
test-paper,  and  then  enough  ammonia  to  make  it  de- 
cidedly alkaline.  Should  a  precipitate  of  magnesium 
hydrate  occur,  make  the  solution  acid  again  with  hydro- 
chloric acid,  and  then  alkaline  again  with  ammonia,  as  be- 
fore. Repeat  this  treatment  if  necessary  until  ammonia 
no  longer  produces  a  precipitate.  Allow  the  fluid  to 
cool,  and  add  16  c.  c.  of  a  solution  of  hydro-disodium 
phosphate,  prepared  by  dissolving  1  part  by  weight  of  the 
salt  in  10  parts  of  water.  Agitate  the  contents  of  the 
beaker  well  with  a  glass  rod,  being  careful  not  to  rub  the 
sides  of  the  vessel  with  the  rod,  as  it  will  cause  crystals  of 
ammonia-magnesium  phosphate  to  adhere  to  the  glass  so 
tenaciously  as  to  be  difficult  to  remove.  Allow  the  solution 
to  stand  cold  12  hours,  and,  when  the  precipitate  has  en- 
tirely settled,  place  3  or  4  drops  of  the  clear  fluid  on  a  watch- 
glass,  or  in  a  very  small  test-tube,  and  add  2  or  3  drops  of 
" magnesia  mixture."  If  a  precipitate  forms,  it  shows 
that  enough  hydro-disodium  phosphate  has  been  used  ;  if 
no  precipitate  forms,  add  5  c.  c.  of  the  precipitant  to  the 
main  solution,  and  proceed  as  before.     Filter  on  a  very 


18  MAGNESIUM  SULPHATE. 

small  filter,  and  wash  with  dilute  ammonia,  prepared  by 
mixing  1  part  of  strong  ammonia  with  2  parts  of  water, 
until  no  turbidity  is  produced  by  silver  nitrate  in  1  c.  c. 
of  the  washings  acidulated  with  nitric  acid,  or  by  barium 
chloride  in  the  same  quantity  acidulated  with  hydro- 
chloric acid.  Dry  the  precipitate  on  the  filter,  and,  when 
it  is  dry,  brush  it  from  the  filter  into  a  large  watch-glass, 
and  burn  the  filter  in  a  weighed  crucible.  When  the  car- 
bon of  the  filter  is  entirely  consumed,  transfer  the  pre- 
cipitate to  the  crucible,  and  ignite  again,  increasing  the 
heat  to  bright  redness,  keeping  the  crucible  covered.  Then 
remove  the  cover,  and  heat  strongly,  until  the  contents  of 
the  crucible  are  white,  or  nearly  so.  Should  the  contents 
of  the  crucible  appear  dark  in  color,  moisten  them  with 
a  few  drops  of  nitric  acid ;  evaporate  off  the  excess  of  acid 
carefully,  and  ignite  again,  until  the  precipitate  is  of  a 
light  gray  color.  Cool  the  crucible  and  contents  in  a 
desiccator,  and  weigh.  Deduct  the  known  weights  of 
the  crucible  and  filter-ash.  The  remainder  will  be  the 
weight  of  the  magnesium  pyro-phosphate  (Mg2P207). 
From  this  weight  calculate  the  per  cent  of  magnesia. 

For  the  determination  of  the  S03  dissolve  1  gm.  in  100 
c.  c.  warm  water,  acidulate  slightly  with  hydrochloric 
acid,  boil,  add  12  c.  c.  of  a  solution  of  barium  chloride — 
prepared  by  dissolving  1  part  by  weight  of  crystallized 
barium  chloride  in  10  parts  of  water — and  continue  the 
boiling  for  2  or  3  minutes.  Allow  the  precipitate  to  settle, 
and  test  a  few  drops  of  the  clear  fluid  with  sulphuric  acid. 
If  no  precipitate  is  produced  by  the  sulphuric  acid,  there 
cannot  be  an  excess  of  barium  chloride  in  the  solution.  In 
such  a  case,  add  another  c.  c.  of  barium  chloride  solution, 
stir,  and  allow  the  precipitate  to  settle,  and  test  again. 
Proceed  in  the  same  way,  until  the  appearance  of  a  pre- 
cipitate upon  testing  shows  that  there  is  a  sufficient  quan- 
tity of  barium  chloride  present.  Finally,  allow  the  pre- 
cipitate to  settle,  decant  the  clear  fluid  on  a  filter,  pour  on 
the  precipitate  100  c.  c.  of  boiling  water  containing  2  or  3 


WATER   OF   CRYSTALLIZATION.  19 

c.  c.  of  hydrochloric  acid,  stir,  allow  the  precipitate  to 
settle,  and  again  decant  on  the  filter.  Repeat  this  treat- 
ment, and  then  transfer  the  precipitate  to  the  filter  with 
hot  water,  and  wash  with  the  same  until  a  few  drops  of 
the  wash-water  show  no  turbidity  when  treated  with 
silver  nitrate,  and  leave  no  more  residue,  when  evaporated 
on  platinum  and  ignited,  than  will  be  left  by  a  similar 
quantity  of  distilled  water,  treated  in  the  same  way.  Dry 
the  precipitate,  brush  it  on  a  clock-glass,  burn  the  filter 
moistened  with  a  few  drops  of  sulphuric  acid  in  a  weighed 
crucible,  add  the  precipitate,  ignite  strongly,  cool,  and 
weigh.  Deduct  the  known  weights  of  the  crucible  and 
filter-ash.  The  remainder  will  be  the  weight  of  the  barium 
sulphate.     From  this  calculate  the  per  cent  of  S03. 

As  the  precipitate  of  barium  sulphate  has  a  tendency  to 
carry  down  with  it  barium  chloride,  which  it  is  difficult  to 
remove  by  washing,  after  igniting  the  precipitate,  brush  it 
from  the  crucible  into  a  beaker,  moisten  with  a  few  drops 
of  hydrochloric  acid,  add  water,  and  boil.  Then  transfer 
all  to  a  filter,  wash  well,  dry,  ignite,  and  weigh.  Where 
barium  sulphate  has  been  precipitated  in  a  fluid  contain- 
ing salts  of  iron,  it  is  nearly  impossible  to  purify  it  in  this 
manner.  In  such  a  case,  fuse  the  ignited  precipitate  with 
a  little  sodium  carbonate,  digest  the  mass  with  boiling 
water  until  it  is  disintegrated,  transfer  it  to  a  filter,  and 
wash  well.  By  this  means,  the  barium  will  remain  on  the 
filter  as  carbonate,  with  the  impurity,  while  the  sul- 
phuric acid  will  pass  into  the  filtrate,  from  which  it  can 
be  precipitated  free  from  impurity. 

For  the  determination  of  the  water,  introduce  about  1 
gm.  of  the  salt  into  a  weighed  crucible,  heat  to  redness, 
cool,  and  weigh.  Again  heat,  cool,  and  weigh.  Repeat 
until  the  crucible  and  contents  no  longer  lose  weight  by 
being  heated.  The  difference  between  the  weights  of  the 
crucible  and  contents,  before  and  after  heating,  is  due  to 
the  loss  of  water.  From  this,  calculate  the  per  cent  of 
water. 


CHAPTER  III. 

CaC03. 


The  theoretical  composition  of  calcite  is :  • 

CaO 56.00  per  cent. 

C02 44.00     "      " 


100.00 

For  the  determination  of  the  lime,  dissolve  1  gm.  in  3 
c.  c.  of  strong  hydrochloric  acid,  and  25  c.  c.  of  boi^g 
water.  It  should  dissolve  completely ;  should  it  not,  filter,** 
ont  any  residue,  and.wash  with  about  50  c.  c.  of  hot  water. 
Then  wash  the  residue  from  the  filter  into  a  very  small 
beaker  with  as  little  water  as  possible,  and  add  2  c.  c.  of 
hydrochloric  acid,  and  boil.  Should  it  dissolve,  add  the 
solution  to  the  first  one  ;  should  it  not  dissolve,  pass  the 
fluid  through  the  same  filter,  wash,  and  add  the  filtrate  to 
the  firs+  solution.  The  combined  solutions  should  not 
amount  to  more  than  200  c.  c.  Dry  the  insoluble  residue, 
burn  it  in  a  weighed  crucible,  and  deduct  its  weight  from 
the  original  weight  of  substance.  The  difference  expresses 
the  actual  weight  of  calcite  taken  for  analysis.  To  the 
combined  solutions  add  enough  ammonia  to  make  the 
fluid  decidedly  alkaline  to  test-paper,  heat  to  boiling,  and 
add  50  c.  c.  of  ammonium  oxalate  solution,  prepared  by 
dissolving  1  part  by  weight  of  the  salt  in  24  parts  of  water. 
Boil  hard  for  two  or  three  minutes.  Then  remove  the 
heat,  allow  the  fluid  to  cool  and  the* precipitate  to  settle. 
To  be  sure  that  enough  ammonium  oxalate  has  been  used, 
put  3  or  4  drops  of  the  clear  fluid  on  a  watch-glass 
or  in  a  small  test-tube,  add  1  drop  of  ammonia  and  two  or 
three  drops  of  solution  of  calcium  chloride.  The  forma- 
tion of  a  precipitate  proves  that  enough  ammonium  ox- 
alate was  used  in  the  first  instance.     If  no  precipitate 


LIME  21 

forms,  add  10  c.  c.  more  ammonium  oxalate  to  the  main 
solution,  and  test  again  in  the  same  way.     Proceed  in  this 
manner  until  assured  that  enough  of  the  precipitant  has 
been  added.     When  the  precipitate  has  thoroughly  set- 
tled, decant  the  clear  fluid  on  a  filter,  after  pouring  off  as 
much  of  the  fluid  as  possible.     Without  disturbing  the 
precipitate,  remove  the  beaker  containing  the  filtrate,  and 
place  another  under  the  funnel.     Then  transfer  the  pre- 
cipitate to  the  filter  with  hot  water,  and  wash  it  down  into 
the  point.     More  washing  than  will  effect  that  object  is 
unnecessary,  as  the  impurities  that  may  possibly  be  pres- 
ent,  that  is,    ammonium  chloride   and   oxalate  will  be 
expelled  by  the  after-treatment  of  the  calcium  oxalate 
with  sulphuric  acid.      The  object  aimed  at   in   remov- 
ing the  beaker  containing  the  filtrate  is  to  avoid  having  to 
re-filter  a  large  amount  of  fluid,  should  the  precipitate  of 
calcium  oxalate  run  through  the  filter,  as  it  sometimes 
does,   particularly  when  the    filter-paper  is    very  thin. 
Remove  any  calcium  oxalate  adhering  to  the  walls  of 
the  beaker  with  a  feather  or  rubber.     If  any  adhere  so 
tenaciously  as  to  render  it  impossible  to  remove  it  with  a 
rubber,  wash  it  off  with  a  little  dilute  hydrochloric  acid 
into  a  small  beaker ;    add   ammonia   to  alkaline  reac- 
tion, a  few  drops  of  ammonium* oxalate,  and  boil  two  or 
three  minutes.     When  the  precipitate  has  settled,  filter 
through  the  same  filter.     The  water  required  to  transfer 
the  precipitate  to  the  filter  will  wash  it  sufficiently.     Dry 
the  filter  and  contents  at  a  temperature  not  exceeding  100° 
C,  to  avoid  making  the  filter  brittle.     When  the  precip- 
itate is  dry,  brush  it  into  a  clock-glass,  cleaning  the  filter 
as  thoroughly  as  possible.     Burn  the  filter  in  a  weighed 
crucible  until  only  white  ash  is  left.     Remove  the  heat, 
and  when  the  crucible  is  cool,  transfer  the  precipitate  from 
the  glass  to  the  crucible,  add  enough  strong  pure  sulphuric 
acid  to  moisten  the  precipitate,  place  the  lid  on  the  crucible 
and  expel  the  excess  of  sulphuric  acid  by  heating  over  a 
Bunsen  burner,  allowing  the  flame  to  touch  only  the  lip 


22 


CALCIUM   CAKBONATE. 


or  edge  of  the  crucible  cover.  After  expelling  all  free  sul- 
phuric acid,  ignite  strongly  for  a  few  minutes,  cool  in  a 
desiccator,  and  weigh.  This  weight,  after  deducting  the 
known  weights  of  crucible  and  filter-ash,  will  be  that  of 
calcium  sulphate.  From  this  calculate  the  per  cent  of 
lime. 

The  filter  should  be  cleaned  as  thoroughly  as  possible, 
as  ignition  will  convert  any  adhering  calcium  oxalate  into 
calcium  hydrate  or  carbonate  which  will  effervesce  vio- 
lently upon  the  addition  of  sulphuric  acid,  thereby  causing 
loss  of  substance,  by  projecting  it  from  the  crucible.  The 
reaction  between  calcium  oxalate  and  sulphuric  acid  takes 
place  without  any  violent  action. 

The  carbonic  acid  is  determined  by  loss  of  weight  of  the 
substance  after  expelling  the  gas,  or  by  weighing  the  gas 
after  absorbing  it  in  potassium  hydrate,  or  soda-lime. 

There  are  a  great  many  kinds  of  apparatus  devised  by 
chemists  for  determining  carbonic  acid  by  loss.  One 
which  every  one  can  prepare  for  himself,  is  constructed  of 
3  small  flasks,  A,  B,  and  (7,  two  of  which,  A  and  B,  hold 
about  100  c.  c.  each,  and  the  third,  or  C,  about  25  c.  c. 


Each  flask  is  provided  with  a  doubly -perforated  cork,  or 
rubber  stopper.  Through  the  first  hole  of  the  stopper  of 
flask  A  passes  a  piece  of  small  glass  tubing,  about  one 


CARBON   DIOXIDE.  23 

and  a  half  inches  long.  Through  the  other  hole,  passes, 
nearly  to  the  bottom  of  the  flask,  one  limb  of  a  glass  tube 
bent  twice  at  right  angles,  the  other  limb  of  which  passes 
through  the  first  hole  of  the  stopper  of  the  other  100  c.  c. 
flask,  B,  nearly  to  the  bottom.  Through  the  other  hole  of 
the  stopper  of  flask  B,  sufficiently  far  to  clear  the  stopper, 
passes  the  short  limb  of  a  tube,  bent  twice  at  right  angles, 
while  the  longer  limb  passes  through  the  first  hole  of  the 
stopper  of  the  25  c.  c.  flask,  (7,  nearly  to  the  bottom. 
Through  the  other  hole,  passes  a  short  tube,  about  one  and 
a  half  inches  long.  Into  flask  A,  introduce  30  c.  c.  of  dilute 
nitric  acid ;  into  flask  B,  a  carefully- weighed  quantity  of 
the  calcium  carbonate  (about  1  gm.),  and  into  flask  O,  10 
c.  c.  of  concentrated  sulphuric  acid.  Put  the  apparatus 
together,  and  weigh.  Then  draw  a  little  acid  over  from  A 
into  B,  by  sucking  at  the  exit  tube  of  (7,  and  close  the 
open  tube  of  A  by  placing  over  it  a  short  piece  of  rubber 
tubing,  the  other  end  of  which  is  closed  by  a  piece  of  glass 
rod.  When  the  violent  effervescence  is  over,  open  the 
closed  tube  of  A,  and  repeat  the  operation,  until  enough 
acid  is  drawn  from  A  into  B  to  decompose  the  calcium 
carbonate.  Then  close  the  open  tube  of  A,  and  raise  the 
contents  of  the  flask  B,  to  incipient  boiling.  Then  re- 
move the  heat ;  at  the  same  time,  remove  the  stopper  from 
the  open  tube  of  A,  attach  in  its  place  a  small  calcium- 
chloride  tube,  containing  equal  parts  of  calcium  chloride 
and  soda  lime,  and  draw  a  gentle  current  of  air  through 
the  apparatus  by  means  of  an  aspirator.  The  air  should 
not  pass  more  rapidly  than  at  the  rate  of  2  bubbles  in  a 
second,  or  the  aspiration  be  continued  longer  than  is  nec- 
essary to  clear  the  apparatus  of  carbonic  acid.  The  pas- 
sage of  half  a  litre  of  air  will  effect  this.  The  amount  can 
be  determined  by  the  volume  of  water  that  escapes  from 
the  aspirator.  The  carbonic  acid  can  be  sucked  out  by  the 
mouth.  If  this  plan  be  adopted,  the  air  should  be  drawn 
through  until  it  no  longer  tastes  of  carbonic  acid.  After 
a  sufficient  volume  of  air  has  been  drawn  through  the 


24  Cj^CITJM  carbonate. 

apparatus  to  extract  the  carbonic  acid,  allow  the  apparatus 
to  cool,  remove  the  aspirator,  if  one  has  been  used,  and 
the  calcium-chloride  tube  from  the  open  tube  of  flask  Ay 
and  weigh.  The  difference  between  this  and  the  first 
weight  of  the  apparatus  is  equivalent  to  the  weight  of 
carbonic  acid.  In  many  cases,  the  determination  of  car- 
bonic acid  by  loss  is  inadmissible.  It  such  cases,  it  is 
absorbed  in  some  substance  with  which  it  will  combine,  as 
potassium  hydrate  or  soda-lime.  For  this  purpose,  an 
apparatus  such  as  that  described  by  Fresenius  in  his 
work  on  Quantitative  Analysis  (§  139  e  p.  293),  under  the 
head  of  carbonic  acid,  can  be  used.  In  making  the  de- 
termination, do  not  use  more  than  0.500  gm.  of  calcium 
carbonate,  as  a  large  quantity  necessitates  the  use  of 
large  absorption  tubes.  If  soda-lime  be  used,  it  is  well 
not  to  use  the  tube  after  more  than  one  half  of  the  con- 
tents have  been  heated  by  the  carbonic  acid. 

For  the  analysis,  weigh  the  absorption  tubes,  introduce 
the  weighed  substance  into  the  decomposing  flask,  put 
the  apparatus  together,  close  the  stop-cock  of  the  funnel- 
tube,  and  attach  the  aspirator.  After  the  aspirator  has 
drawn  long  enough  to  produce  a  partial  vacuum  in  the 
apparatus,  introduce  about  30  c.  c.  of  dilute  nitric  acid, 
through  the  funnel-tube,  into  the  decomposing-flask.  As 
soon  as  all  the  acid  is  in,  close  the  funnel-tube.  After  the 
first  violent  effervescence  has  ceased,  apply  gentle  heat  to 
the  flask,  and  gradually  increase  it,  until  the  fluid  in  the 
flask  begins  to  boil.  Then  remove  the  heat,  attach  the 
guard  tube,  containing  soda  lime  and  calcium  chloride, 
open  the  stop-cock  or  clamp,  and  draw  air  through  the 
apparatus,  very  slowly,  until  the  absorption  tubes  are 
cool,  or  until  about  2  litres  of  air  have  passed  through. 
When  the  tubes  are  cool,  weigh  them.  The  difference  be- 
tween this  weight  and  the  first  weight  of  the  tubes  is 
equivalent  to  the  carbonic  acid.  The  carbonic  acid  can 
also  be  determined  by  introducing  a  weighed  quantity 
into  a  tube  of  hard  glass,  by  means  of  a  small  platinum 


CARBON   DIOXIDE. 


25 


boat,  and  igniting  strongly,  at  the  same  time,  drawing 
through  the  tube  a  current  of  dried  air.  Attach  to  the 
tube  a  weighed  tube,  filled  with  neutral  calcium  chloride, 
over  which  carbon  dioxide  has  been  passed  for  some  time. 
This  will  absorb  the  water,  and  allow  the  carbonic  acid  to 
pass.  After  the  carbonic  acid  is  expelled  from  the  sub- 
stance, weigh  both  the  boat  and  contents,  and  also  the 
calcium-chloride  tube.  The  loss  of  weight  of  the  boat 
will  be  carbonic  acid  plus  water,  while  the  increase  of 
weight  of  the  calcium-chloride  tube  will  be  water.  The 
difference  between  the  weight  of  carbonic  acid  and  water, 
determined  by  loss,  and  the  weight  of  water  will  be  that 
of  carbonic  acid.  Not  more  than  0.500  gm.  of  substance 
should  be  used. 


Note. — The  apparatus  used  in  the  estimation  of  the  carbonic  acid  is  repre- 
sented below. 


a  contains  soda-lime  ;  it  can  be  attached  to  b  with  a  cork,  b  is  provided  with 
a  glass  tap.  The  flask  c  has  a  capacity  of  200  c.  c.  d  contains  sulphuric  acid,  e 
contains  pumice  saturated  with  sulphuric  acid,  /contains  pumice  which  has 
been  saturated  with  solution  of  sulphate  of  copper,  and  then  heated  strongly  till 
all  the  water  has  been  expelled,  g  contains  soda-lime  and  h  sulphuric  acid  on 
pumice.  The  pumice  used  in  this  apparatus  should  be  previously  heated  with 
strong  sulphuric  acid,  washed  and  dried,  as  it  is  liable  to  contain  chlorides  and 
fluorides.  The  loose  sulphuric  acid  in  the  U  tubes  should  not  rise  above  the  bend 
when  at  rest. 

g  and  h  are  the  only  pair  in  the  train  which  are  weighed.  They  should  be 
provided  with  rubber  tubes,  stopped  with  glass  rod  to  prevent  absorption  of 
carbonic  acid  or  moisture  from  the  air. 


CHAPTER  IV. 

POTASSIUM      ALUM. 

AlK(SO±)2.12IT20. 
The  theoretical  composition  of  potassium  alum  is : 

A1203 10.86  per  ceni. 

K20 9.90    "       •< 

S03 33.72    "       •' 

H20 45.52     "       " 

100.00 

Pulverize  5  or  6  gms.  coarsely  and  quickly,  and  keep 
the  powder  in  a  small  corked  bottle,  or  specimen  tube. 
For  the  determination  of  alumina,  first  weigh  the  tube, 
and  contents  ;  then  shake  out  a  little  into  a  beaker,  and 
again  weigh  the  tube,  and  remaining  substance.  The 
diminution  in  weight,  of  course,  shows  the  amount  taken. 
Proceed  in  this  way  until  about  1  gm.  has  been  trans- 
ferred to  the  beaker.  Pour  upon  it  100  c.  c.  of  hot  water 
and  stir  ;  when  all  is  dissolved,  add  2  or  3  c.  c.  of  strong 
hydrochloric  acid,  and  enough  ammonia  to  turn  red  test- 
paper  blue,  and  emit  a  slight  odor  of  ammonia.  Be 
cautious  not  to  add  a  large  excess,  or  time  will  be  wasted 
in  boiling  it  out,  which  will  be  necessary  for  the  reason 
that  aluminum  hydrate  is  somewhat  soluble  in  excess  ol 
ammonia.  Boil  until  the  vapors  no  longer  smell  of 
ammonia,  and  do  not  turn  turmeric  paper  brown.  Allow 
the  precipitate  to  settle,  and  decant  the  clear  fluid  on  a 
filter.  Then  pour  40  or  50  c.  c.  of  boiling  water  on  the 
precipitate,  stir,  allow  it  to  settle,  and  decant  the  clear 
fluid  on  the  filter  as  before.  Repeat  this  treatment  several 
times,  and  finally  transfer  the  precipitate  to  the  filter, 
with  boiling  water,  and  wash  with  the  same,  until  a  few 
drops  of  the  wash-water,  acidulated  with  nitric  acid,  do 
not  show  a  precipitate  of  silver  chloride  when  treated  with 


i0T  POTASSIUM.  27 

a  drop  of  silver  nitrate,  or  a  precipitate  of  barium  sul- 
phate when  treated  with  hydrochloric  acid  and  barium 
chloride.  It  is  unnecessary  to  begin  washing  on  the  filter 
until  about  1 00  c.  c.  have  passed  through  the  filter.  Test 
the  filtrate  and  washings  with  litmus  paper.  If  they  are 
not  alkaline,  add  ammonia  until  the  fluid  is  faintly  alka- 
line, and  heat.  Should  a  precipitate  appear,  filter  it  out, 
wash,  dry  it,  and  reserve  it  to  be  burned  with  the  other. 
When  the  main  precipitate  is  perfectly  dry,  ignite  it,  with 
the  smaller  one,  should  there  be  any,  rolled  up  in  the 
filter,  in  a  weighed  crucible  furnished  with  a  lid,  apply- 
ing the  heat  gently  at  first,  and  then  intensely,  in  order  to 
expel  any  adhering  sulphuric  acid.  During  the  latter 
part  of  the  ignition  remove  the  cover  from  the  crucible,  in 
order  thoroughly  to  consume  the  filter.  When  the  filter 
is  completely  burned,  remove  the  heat,  cool  and  weigh. 
This  weight,  after  deducting  the  weight  of  the  crucible 
and  filter-ash,  will  be  the  weight  of  the  alumina. 

For  the  determination  of  S03  concentrate  the  filtrate 
from  the  alumina  to  200  c.  c.  by  evaporation,  add  hydro- 
chloric acid  until  the  fluid  is  slightly  acid,  and  then  add 
12  c.  c.  of  barium  chloride  solution,  prepared  by  dissolv- 
ing 1  part  by  weight  of  crystallized  barium  chloride  in  10 
parts  of  water.  Boil  for  a  few  minutes  and  allow  the  pre- 
cipitate of  barium  sulphate  to  settle,  and  proceed  as  di- 
rected in  the  analysis  of  magnesium  sulphate.  Observe 
the  precautions  there  given,  as  to  washing  and  purification 
of  the  precipitate. 

To  determine  the  potassium,  add  ammonia  to  the  filtrate 
from  the  barium  sulphate  until  it  is  slightly  alkaline, 
heat  to  boiling,  and  add  ammonium  carbonate  as  long  as 
it  produces  a  precipitate  of  barium  carbonate.  When  all 
the  barium  is  precipitated,  decant  the  clear  fluid  on  a 
filter,  wash  by  decantation  3  or  4  times,  using  about  50 
c.  c.  of  hot  water  each  time,  transfer  the  precipitate  to  the 
filter,  and  wash  it  well  with  hot  water,  or  until  2  or  3 
drops  of  the  wash- water,  acidified  with  nitric  acid,  show 


28  POTASSIUM    ALUM. 

no  cloudiness  when  treated  with  silver  nitrate.  Pour  3  or 
4  funnelfuls  through  the  filter  before  beginning  to  test. 
When  all  the  potassium  chloride  is  washed  out,  evaporate 
the  filtrate  and  washings  to  dryness  in  a  platinum  dish, 
and  ignite  to  faint  redness,  until  all  the  ammonium 
chloride  is  expelled.  This  may  be  ascertained  by  holding 
over  the  vessel  a  clean  cold  clock-glass.  The  non-appear- 
ance of  a  white  coating  on  the  glass  indicates  the  absence 
of  ammonium  chloride.  Dissolve  the  residue  in  about  25 
c.  c.  of  warm  water,  filter  the  solution  into  a  small  porce- 
lain dish,  and  wash  with  hot  water,  testing  the  wash-water 
with  silver  nitrate,  as  directed  above,  to  be  sure  that  all 
potassium  chloride  is  washed  out.  When  the  filter  and 
contents  are  sufficiently  washed,  add  to  the  fluid  2  drops 
of  concentrated  hydrochloric  acid  and  8  c.  c.  of  platinum 
tetrachloride  solution,  prepared  by  dissolving  1  part  by 
weight  of  platinum  tetrachloride  in  10  parts  of  water,  and 
evaporate  to  a  pasty  consistency,  on  a  water-bath.  Then 
pour  into  the  dish  about  50  c.  c.  of  alcohol,  of  about  85 
per  cent,  without  removing  the  dish  from  the  bath,  and 
heat  for  two  or  three  minutes.  Then  wash  the  contents  of 
the  dish  into  a  small  flask,  marked  A,  with  alcohol  of  85 
per  cent,  and  cork  it  immediately,  to  avoid  the  possibility 
of  absorption  of  ammonia  from  the  air  of  the  laboratory,  of 
which  there  is  frequently  great  danger.  After  the  potas- 
sium platino-chloride  has  entirely  settled,  and  the  fluid 
shows  by  its  color  that  a  sufficient  amount  of  platinum 
tetrachloride  has  been  added,  pour  off  the  clear  fluid  into 
another  flask,  marked  B,  as  completely  as  possible  with- 
out transferring  any  of 'the  precipitate,  cork  it,  and  allow 
it  to  stand  long  enough  for  any  particles  of  potassium 
platino-chloride,  which  may  have  passed  over  with  the 
fluid  from  flask  A,  to  subside.  Then  pour  into  the  first 
flask,  A,  20  or  30  c.  c.  of  85  per  cent  alcohol,  cork  it,  and 
after  agitating  it  gently  set  it  aside,  until  the  contents  of 
the  flask  B  are  disposed  of.  Pour  the  contents  of  B  into 
a  dish,  add  about  10  c.  c.  of  water,  and  proceed  to  evapo- 


POTASSIUM.  29 

rate  off  the  alcohol  on  a  water-bath.  Should  there  be  any 
particles  of  the  precipitate  in  the  fluid,  first  pour  off  as 
much  as  possible  into  the  dish,  without  disturbing  the 
precipitate,  and  evaporate  it  as  above,  and  pour  the  rest, 
with  the  precipitate,  on  a  filter.  Add  this  filtrate  to  the 
fluid  already  evaporating.  Keep  the  funnel  covered  with 
a  glass  while  filtering.  After  all  the  fluid  has  thus  been 
transferred  to  the  dish  for  evaporation,  pour  upon  the 
same  filter  the  contents  of  flask  A,  washing  the  precipitate 
into  the  filter  with  85  per  cent  alcohol.  Dry  the  filter 
and  contents  in  an  air-bath  at  100°  C.  Ignite  the  dry  pre- 
cipitate, rolled  up  in  the  filter,  in  a  weighed  crucible, 
applying  the  heat  very  gently  at  first,  and  keeping  the 
crucible  covered  until  the  filter-paper  is  charred.  Then 
remove  the  cover  from  the  crucible,  and  ignite  at  a  higher 
degree  of  heat,  until  the  filter  is  entirely  consumed. 
Allow  the  crucible  to  cool,  add  a  little  oxalic  acid,  heat 
gently  at  first,  until  the  water  of  crystallization  of  the 
oxalic  acid  is  expelled,  and  then  more  intensely  until  the 
acid  is  decomposed,  and  all  the  carbon  consumed.  Cool 
the  crucible,  and  wash  by  decantation  with  hot  water  as 
long  as  the  wash- water  becomes  turbid  from  formation  of 
silver  chloride,  when  treated  with  silver  nitrate.  By  this 
means,  the  double  chloride  is  decomposed,  and  all  the 
potassium  and  chlorine  washed  out,  leaving  only  spongy 
platinum.  Heat  alone  fails  to  decompose  the  compound 
completely. 

After  the  platinum  is  sufficiently  washed,  dry  the  cru- 
cible and  contents,  and  ignite  until  every  thing  is  con- 
sumed but  spongy  platinum.  Cool,  and  weigh.  Deduct 
from  this  weight,  that  of  the  crucible  and  filter-ash.  The 
remainder  will  be  the  weight  of  platinum.  From  this, 
calculate  the  per  cent  of  potassium  or  of  potassium  oxide. 

After  all  the  alcohol  has  been  expelled  from  the  original 
filtrate  by  evaporation,  as  directed  above,  add  1  c.  c.  of 
platinum  tetrachloride  solution,  and  a  very  small  quantity 
of  pure  sodium  chloride ;    continue  the    evaporation  to 


30  POTASSIUM  ALUM. 

pasty  consistency,  treat  with  alcohol,  and  proceed  as 
directed  for  the  treatment  of  the  main  precipitate.  Should 
any  more  potassium  platino-chloride  be  obtained,  treat  it 
as  above,  and  add  the  per  cent  to  that  of  the  main  pre- 
cipitate. The  sodium  chloride  tends  to  prevent  the  de- 
composition of  the  platinum  chloride,  while  evaporating 
the  alcoholic  solution. 

Instead  of  igniting  the  dry  precipitate  ,of  potassium 
platino-chloride,  it  may  be  weighed  as  such.  In  this  case, 
filter  through  an  exhausted  filter  ;  that  is,  one  which  has 
been  previously  washed  with  hydrochloric  acid,  and  then 
with  water  until  all  the  acid  is  removed  from  the  paper. 
Then  dry  the  filter  between  watch-glasses,  held  together 
by  a  clip.  After  weighing  the  glasses,  clip,  and  paper  to- 
gether, previously  dried  at  100°  C,  transfer  the  filter  to  a 
funnel,  and  filter  the  solution  through  it.  Dry  the  filter 
and  precipitate  first  in  the  funnel  at  100°  C.  Then  place 
them  between  the  glasses,  secure  the  glasses  by  means  of 
the  clip,  dry  again  at  100°  C,  cool,  and  weigh.  The  in- 
crease in  weight  will  be  that  of  the  precipitate  of  potas- 
sium platino-chloride.  From  this,  calculate  the  per  cent 
of  potassium.  This  method  is  tedious  and  objectionable 
where  a  small  quantity  of  potassium  platino-chloride  is 
to  be  dealt  with.  If  great  care  is  exercised  in  preparing 
and  drying  the  filter,  it  may  be  adopted  where  a  large 
amount  of  potassium  is  to  be  determined. 

For  the  determination  of  water,  weigh  about  1  gm. 
shaken  from  the  tube,  as  directed  above,  into  a  weighed 
crucible,  heat  to  250°  C,  cool,  and  weigh.  Repeat  the 
heating  and  weighing  until  the  substance  ceases  to  lose 
weight.  The  loss  of  weight  is  equivalent  to  the  weight  of 
water  expelled.  From  this,  calculate  the  per  cent  of 
water. 


CHAPTER    V. 

CALCIUM   FLUOEIDE. 

CaM2. 

The  theoretical  composition  is  : 

Ca 51.28  per  cent. 

Fl 48.72    " 


100.00 

Introduce  into  a  weighed  platinum  crucible  1  gm.  of 
the  finely -powdered  mineral,  mix  it,  by  means  of  a  coarse 
platinum  wire,  with  pure  concentrated  sulphuric  acid,  to 
the  consistence  of  paste  ;  add  enough  more  acid  to  make 
the  mixture  semi-fluid,  place  the  crucible  with  the  cover 
on,  in  an  inclined  position  on  a  support,  and  heat  with  a 
Bunsen  burner,  allowing  the  flame  to  strike  the  edge  of 
the  crucible  and  lid.  Continue  heating  until  all  the  sul- 
phuric acid  is  expelled,  and  the  calcium  converted  into 
sulphate,  cool,  weigh,  and  calculate  the  weight  of  calcium. 
The  difference  between  the  weight  of  calcium  and  the 
weight  of  mineral  taken  is  equivalent  to  the  weight  of 
fluorine  expelled.  From  these  data,  calculate  the  per  cent 
of  calcium  and  fluorine. 

There  are  various  methods  for  determining  fluorine, 
varying  in  complexity  with  the  character  of  the  sub- 
stances treated.  It  was  suggested  by  Berzelius  (Rose,  p. 
883)  to  distill  the  fluoride  of  silicon  from  substances  that 
could  be  decomposed  by  sulphuric  acid,  by  heating  with 
this  acid,  adding  powdered  silica  if  necessary,  in  a  retort 
of  lead  or  platinum,  delivering  into  a  vessel  of  water.  The 
acid  used  must  be  pure  and  concentrated,  the  silica  pure 
and  in  the  form  of  very  fine  powder,  and  the  metallic  tube 
connected  with  the  retort  must  dip  into  mercury  just  far 
enough  to  prevent  the  point  from  coming  in  contact  with 


32  CALCIUM   FLUOEIDE. 

the  water,  or  the  separated  silica  will  clog  it.  The  fluoride 
of  silicon,  when  it  comes  in  contact  with  the  water,  is 
decomposed  into  silica,  which  separates,  and  hydro-fluo- 
silicic  acid,  which  goes  into  solution.  Filter  out  the  silica, 
wash  it  well,  dry,  and  weigh  it.  To  the  acid  fluid 
containing  hydro-fluosilicic  acid,  Rose  (lb.  p.  883)  adds 
potassium  chloride  and  alcohol.  The  potassium  silico- 
fluoride  is  collected  on  a  weighed  filter,  washed  with 
dilute  alcohol,  consisting  of  equal  parts  of  alcohol  and 
water,  dried  at  100°  C,  and  weighed.  The  fluorine  calcu- 
lated from  the  silica,  and  from  the  precipitate  of  potas- 
sium silico-fluoride,  will  together  give  the  per  cent  in  the 
substance. 

SSiF,  +  3&20  =  lI2SiOB  +  2B2SiF6. 

To  determine  the  fluorine  in  substances  insoluble  in 
water,  and  not  decomposable  by  acid,  Berzelius  (Vid. 
Fres.  Quant.,  §  166a)  fused  the  substance  with  4  parts 
of  sodium  carbonate  at  a  strong  red  heat,  digested  the 
mass  in  water,  boiled,  filtered,  and  washed,  first  with 
boiling  water,  then  with  a  solution  of  ammonium  car- 
bonate. The  filtrate  will  contain  all  the  fluorine  as 
sodium  fluoride,  together  with  carbonate,  silicate,  and 
aluminate  of  sodium.  The  filtrate  is  to  be  mixed  with 
ammonium  carbonate,  and  the  mixture  heated,  the  am- 
monium carbonate  which  evaporates  being  replaced. 
The  aluminium  hydrate  and  silicic  acid  is  then  filtered  off 
and  washed  with  ammonium  carbonate.  The  filtrate  is 
then  heated  until  the  ammonium  carbonate  is  completely 
expelled,  and  the  fluorine  determined.  Rose  suggests  a 
modification  of  Berzelius' s  treatment  after  reaching  this 
point,  which  is  as  follows  :  Add  a  solution  of  calcium 
chloride  as  long  as  a  precipitate  continues  to  form.  When 
the  precipitate,  which  consists  of  calcium  fluoride,  and 
calcium  carbonate,  has  subsided,  it  is  washed,  first  by 
decantations,  afterward  on  the  filter,  and  dried.  When 
dry,  it  is  ignited  in  a  platinum  crucible.     Water  is  then 


FLUORINE.  33 

poured  over  it,  in  a  platinum  or  porcelain  dish,  acetic 
acid  added  in  slight  excess,  the  mixture  evaporated  to 
dryness  on  a  water-bath,  and  heated  on  the  latter  until 
all  odor  of  acetic  acid  disappears.  The  residue,  which 
consists  of  calcium  fluoride  and  calcium  acetate,  is  heated 
with  water,  the  calcium  fluoride  filtered  off,  washed,  dried, 
ignited,  and  weighed.  If  the  precipitate  of  calcium 
fluoride  and  calcium  carbonate  were  treated  with  acetic 
acid,  without  previous  heating,  the  washing  of  the  fluor- 
ide would  be  very  difficult.  From  the  weight  of  the 
calcium  fluoride,  calculate  the  per  cent  of  fluorine. 
See  H.  Eose,  Anal.  Ohem.,  chapter  on  Fluorine,  p.  757. 


CHAPTER  VI. 

POTASSIUM  IODIDE. 

KL 

The  theoretical  composition  is : 

K 23.545  per  cent. 

1 76.455  "   " 


100.000 

To  determine  the  potassium,  dissolve  1  gm.  of  the  salt 
in  about  10  c.  c.  of  water,  in  a  small  porcelain  dish,  add 
2  or  3  c.  c.  strong  nitric  acid,  and  evaporate  to  dryness  on 
the  water-bath,  to  expel  the  iodine.  It  may  be  necessary 
to  repeat  this  operation  in  order  to  drive  out  the  last  traces 
of  the  iodine.  Take  up  with  about  20  c.  c.  of  water,  add 
1  c.  c.  strong  hydrochloric  acid,  and  proceed  as  directed 
in  the  analysis  of  potassium  alum. 

To  determine  the  iodine,  weigh  carefully  0.250  gm.  of 
the  salt,  transfer  it  to  a  parting  flask,  add  warm  water,  an 
excess  of  silver  nitrate  and  nitric  acid,  and  proceed  as 
directed  in  the  analysis  of  barium  chloride,  for  the  deter- 
mination of  chlorine,  care  being  taken  to  add  excess  of 
silver  nitrate  before  adding  the  nitric  acid. 

The  iodine  can  also  be  determined  with  great  accuracy 
by  precipitating  it,  as  palladium  iodide,  in  a  solution  of 
the  salt,  slightly  acidified  with  hydrochloric  acid,  warm- 
ing gently  and  allowing  the  whole  to  stand  for  about  24 
hours,  to  give  the  precipitate  ample  time  to  form  and 
settle.  It  is  better  finally  to  ignite  the  precipitate,  and 
from  the  metallic  palladium  calculate  the  iodine. 

See  Fres.,  §  145— 1— b,  p.  311,  and  H.  Rose,  chapter  on 
Iodine,  p.  824. 


CHAPTER  VII. 

POTASSIUM   BROMIDE. 

KBr. 
The  theoretical  composition  of  the  salt  is : 

K ..  32. 835  per  cent. 

Br 67.165    "      " 


100.000 

For  the  determination  of  the  potassium,  proceed  exactly 
as  in  the  previous  analysis  of  potassium  iodide,  or  boil 
with  dilute  chlorine  water  until  the  bromine  is  expelled, 
and  then  proceed. 

The  bromine  is  determined  as  silver  bromide,  in  the 
same  manner  as  chlorine  is  determined  as  silver  chloride, 
in  the  analysis  of  barium  chloride. 

See  H.  Hose,  Anal.  Chem.,  chapter  on  Bromine,  p.  815- 


CHAPTER  YIII. 

HYDRO-DISODIUM   PHOSPHATE. 

The  theoretical  composition  of  hydro-disodium  phos- 
phate is : 

Na20 17.32  per  cent. 

P205 19.83    "      " 

HaO 62.85    "      " 

100.00 

Select  4  or  5  gins,  of  the  crystals  which  have  lost  no 
water  by  efflorescence,  break  them  up  quickly  into  a 
coarse  powder,  and  keep  the  powder  in  a  small,  well- 
corked  bottle  or  large  specimen  tube,  and  weigh  the 
portions  required  for  analysis  as  directed  in  the  case  of 
potassium  alum. 

Perhaps  a  better  plan  is  to  dissolve  about  5  gms.  in  100 
c.  c.  of  water,  transfer  the  solution  to  a  250  c.  c.  flask, 
dilute  to  the  holding  mark,  and  mix  the  fluid  well  by 
pouring  several  times  from  the  flask  into  a  beaker  and 
back.  Then  draw  from  the  flask  with  a  pipette  the  quan- 
tity required  for  analysis,  and  cork  the  flask  to  prevent 
evaporation  of  the  fluid. 

For  the  determination  of  sodium,  dissolve  about  1  gm. 
of  the  salt  in  about  50  c.  c.  of  water,  or  take  an  equivalent 
amount  from  the  solution  of  a  large  quantity.  Then  dis- 
solve about  0.600  gm.  piano-forte  wire  in  30  c.  c.  dilute 
hydrochloric  acid,  add  3  c.  c.  of  strong  nitric  acid,  and 
boil.  Then  concentrate  the  solution  until  nearly  all  free 
acid  is  expelled,  dilute  with  10  c.  c.  of  water,  and  add  the 
solution'to  that  of  the  sodium  phosphate.  To  the  com- 
bined solutions  add  ammonia  in  excess,  and  heat  to 
boiling.  Then  remove  the  heat,  and  allow  the  precipitate 
to  settle.     When  the  precipitate  has  settled  thoroughly, 


PHOSPHORIC  ANHYDRIDE.  37 

and  the  supernatant  fluid  become  colorless,  filter  off  the 
clear  fluid,  and  wash  the  precipitate  three  or  four  times, 
using  50  or  60  c.  c.  of  hot  water  each  time.  Then  transfer 
the  precipitate  to  the  filter,  and  wash  again  with  hot 
water,  until  the  washings  show  only  a  slight  opalescence 
upon  addition  of  silver  nitrate  and  nitric  acid.  In  testing 
the -washings,  use  only  2  or  3  drops  each  time.  The 
precipitate  will  contain  all  the  phosphoric  acid,  combined 
with  the  ferric  oxide,  and  may  be  rejected.  Evaporate 
the  filtrate  and  washings  to  dryness  on  a  water-bath.  Just 
before  the  point  of  dryness  is  reached,  add  dilute  hydro- 
chloric acid,  little  by  little,  until  the  fluid  is  slightly  acid 
to  test-paper.  By  delaying  the  addition  of  the  acid  until 
nearly  all  the  ammonia  is  expelled  by  the  evaporation, 
there  will  be  less  ammonium  chloride  to  burn  out,  and  less 
danger  of  loss  of  sodium  chloride  by  ignition.  Continue 
the  evaporation,  and,  when  the  mass  is  perfectly  dry,  ignite 
gently  until  vapor  of  ammonium  chloride  ceases  to  be 
evolved.  Cool,  dissolve  in  a  little  boiling  water,  and  filter 
into  a  weighed  platinum  dish ;  washing  the  filter  until  a 
few  drops  of  the  wash-water  do  not  give  a  precipitate  of 
silver  chloride,  when  treated  with  silver  nitrate.  Then 
evaporate  the  filtrate  to  dryness,  ignite  gently,  and  weigh 
the  sodium  chloride.  From  this  weight,  calculate  the  per 
cent  of  soda.  The  ignited  sodium  chloride  should  be 
white  and  perfectly  soluble  in  water.  -  If  it  is  not,  filter 
the  solution,  wash  the  insoluble  residue,  evaporate  the 
filtrate  and  washings  to  dryness,  ignite,  and  weigh  again. 
For  the  determination  of  phosphoric  acid,  take  1  gm.  of 
the  salt,  weighed  as  directed  in  the  analysis  of  potassium 
alum,  or  a  portion  of  a  solution  of  larger  quantity  equiva- 
lent to  1  gm.  If  1  gm.  of  the  solid  salt  is  taken,  dissolve 
it  in  50  c.  c.  of  cold  water,  acidify  the  solution  with  hy- 
drochloric acid,  and  then  make  it  slightly  alkaline  with 
ammonia.  When  the  solution  is  cool,  add  12  c.  c.  of 
' e  magnesia  mixture, ' '  and  set  it  aside  for  some  hours.  The 
"magnesia  mixture"  is  prepared  by  dissolving  1  part  by 


38  HYDEO-DISODITJM    PHOSPHATE. 

weight  of  crystallized  magnesium  sulphate  and  1  part  by 
weight  of  ammonium  chloride  in  8  parts  of  water  and  4 
parts  of  ammonia.  After  the  precipitate  of  ammonio- 
magnesium-phosphate  has  entirely  settled,  filter,  wash 
with  dilute  ammonia  until  the  washings  give  no  reaction 
for  sulphuric  acid,  and  place  the  funnel  containing  the 
precipitate  in  an  air-hath  to  dry.  Eeserve  the  filtrate  for 
some  hours.  Should  another  precipitate  appear,  filter  it 
out  on  the  smallest-sized  filter,  wash  it  with  20  or  30  c.  c. 
of  dilute  ammonia,  dissolve  it  through  the  filter  with  a 
little  dilute  hydrochloric  acid  into  a  small  beaker,  and 
make  the  solution  alkaline  with  ammonia.  If  the  ammo- 
nia produces  a  precipitate,  filter  it  out,  wash  it  with  dilute 
ammonia,  dry,  and  ignite  with  the  main  precipitate  of 
ammonio-magnesium-phosphate.  Ignition  converts  this 
into  magnesium  pyrophosphate.  From  this,  after  weigh- 
ing and  deducting  the  weight  of  the  crucible  and  filter-ash, 
calculate  the  per  cent  of  PsOG.  It  sometimes  happens 
that,  in  precipitation  of  phosphoric  acid  by  means  of 
magnesia  mixture,  some  magnesium  hydrate  is  precipi- 
tated with  the  phosphate.  When  there  is  reason  to  sus- 
pect that  such  has  been  the  case,  from  the  flocculenfc 
appearance  of  the  precipitate,  dissolve  the  ignited  precipi- 
tate of  pyrophosphate  in  a  little  hydrochloric  acid,  dilute 
slightly,  add  a  few  drops  of  nitric  acid,  and  boil  gently 
for  about  an  hour,  renewing  the  fluid  from  time  to  time. 
.By  this  means,  the  pyrophosphoric  acid  will  be  converted 
into  the  tribasic  acid  again.  Then  make  the  fluid  alkaline 
with  ammonia.  The  ammonio-magnesium-phosphate  will 
be  precipitated  free  from  magnesium  hydrate,  and  is  to  be 
treated  as  directed  above.  It  is  necessary  to  convert  the 
pyrophosphoric  or  tetrabasic  into  the  tribasic  acid  before 
adding  the  ammonia,  as  the  pyrophosphate  is  soluble  to 
an  appreciable  extent  in  ammonia  water. 

For  the  determination  of  the  water,  weigh  1  gm.  of  the 
phosphate  in  a  boat  made  of  platinum  foil.  Introduce  the 
boat  into  a  tube  of  hard  glass  about  8  or  10  inches  long, 


WATER  OF   CRYSTALLIZATION.  39 

such  as  is  used  for  combustion  in  organic  analysis.  One 
end  of  this  tube  is  clojed  by  a  cork,  through  which  passes 
a  short  piece  of  smalleT  glass  tubing,  while  the  other  end  is 
drawn  out  to  a  long  point,  bent  at  a  right  angle  to  the  body 
of  the  tube.  Insert  the  point  into  an  ordinary  calcium 
chloride  tube  previously  filled  and  weighed,  letting  it  pro- 
ject a  short  distance  through  the  cork.  This  arrangement 
is  designed  to  afford  an  uninterrupted  passage  of  the  water 
from  the  ignition-tube  into  the  calcium  chloride,  and  allow 
the  application  of  heat  very  near  the  extreme  point  of  the 
ignition-tube,  to  drive  all  the  water  into  the  absorption- 
tube  containing  anhydrous  calcium  chloride.  Connect 
the  cork  for  the  other  end  of  the  ignition-tube  by 
means  of  rubber  with  another  tube  containing  cal- 
cium chloride.  This  latter  is  intended  to  dry  the  air 
drawn  through  the  apparatus.  After  the  boat  containing 
the  substance  is  introduced  into  the  iglition-tube,  insert 
the  cork,  attach  the  weighed  absorption-tube  to  the  point, 
connect  the  other  end  of  the  absorption-tube  by  means  of 
rubber  tubing  with  an  aspirator,  and  proceed  to  draw  a 
gentle  current  of  air  through  the  apparatus.  Then  apply 
heat  to  the  ignition-tube  sufficient  to  expel  the  water. 
When  this  is  all  drawn  into  the  absorption-tube  detach 
the  aspirator,  allow  the  apparatus  to  cool,  and  weigh  the 
absorption-tube.  The  increase  in  weight  will  be  equiva- 
lent to  the  weight  of  water.  From  this,  calculate  the  per 
cent  as  usual. 


CHAPTER  IX. 

AMMONIO-FERRIC   SULPHATE,    OR  AMMONIA  IRON  ALUM* 

FeJSrHi(SOt)2.12II20. 
The  theoretical  composition  of  the  salt  is : 

Fe203 16.60  per  cent. 

S03 33.20    "      " 

NH3 3.52    "      " 

HaO 46.68    «      " 

100.00 

Select  8  or  10  gms.  of  crystals  which  have  not  lost  water 
by  efflorescence ;  jbreak  them  into  small  pieces  or  coarse 
powder,  and  keep  for  analysis  in  a  small,  well-corked  bot- 
tle.    Consult  analysis  of  hydro-disodium  phosphate. 

For  the  determination  of  the  ferric  oxide  by  precipi- 
tation, take  as  nearly  as  possible  1  gm.  weighed  in  the 
manner  directed  in  the  analysis  of  potassium  alum,  or  an 
equivalent  amount  from  the  solution  of  a  larger  quantity, 
if  the  plan  suggested  in  the  analysis  of  hydro-disodium 
phosphate  be  adopted. 

If  1  gm.  of  the  solid  salt  be  weighed,  dissolve  it  in  100 
c.  c.  hot  water  and  1  c.  c.  dilute  hydrochloric  acid.  When 
the  solution  is  complete,  add  ammonia  (little  by  little) 
until  the  fluid  is  slightly  alkaline,  and  heat  to  boiling. 
Then  remove  the  heat  and  allow  the  precipitate  to  settle  \. 
decant  the  clear  fluid  through  a  filter,  pour  upon  the  pre- 
cipitate 50  c.  c.  hot  water,  stir,  allow  the  precipitate  to 
settle,  and  pour  the  clear  fluid  through  the  filter  as  before. 
Repeat  this  washing  by  decantation  three  times.  Then 
transfer  the  precipitate  to  the  filter  with  hot  water,  and 
wash  with  hot  water  until  the  washings  give  no  precip- 
itate when  treated  with  barium  chloride  solution.  Dry 
the  precipitate  thoroughly,  and  remove  it  from  the  filter 


FEEEIC    OXIDE.  41 

by  i  averting  the  latter  on  a  clock-glass,  and  rubbing  the 
filter  between  the  finjers.  By  this  means,  nearly  all  of  the 
precipitate  can  be  removed  from  the  filter,  without  any 
danger  of  loss  by  brushing.  After  removing  the  precip- 
itate as  cleanly  as  possible,  burn  the  filter  in  a  weighed 
crucible,  after  adding  a  few  drops  of  nitric  acid.  When 
the  carbon  of  the  filter  is  completely  consumed,  brush  the 
precipitate  into  the  crucible,  and  ignite  again,  keeping  it 
covered  until  all  danger  of  decrepitation  is  past.  Then 
remove  the  cover,  and  heat  to  a  bright  red  heat.  After 
heating  intensely  for  some  minutes^emove  the  heat,  cool 
the  crucible  and  contents  in  a  desiccator,  and  weigh. 
From  this  weight,  we  obtain%the  per  cent  of  Fe203  by  de- 
ducting the  weight  of  crucible  and  filter-ash.  If  the  con- 
tents of  the  crucible  should  look  black,  moisten  with  a 
few  drops  of  nitric  acid,  evaporate  off  |he  excess  of  acid 
carefully,  ignite,  cool,  and  weigh  again. 

For  the  determination  of  the  S03  acidulate  the  filtrate 
from  the  ferric  hydrate,  and  proceed  as  in  the  analysis  of 
magnesium  sulphate. 

To  determine  the  ferric  oxide  by  ignition,  introduce 
about  1  gm.  of  the  salt  into  a  previously-weighed  crucible, 
and  heat  gently,  and  then  gradually  increase  the  heat  to 
the  highest  point  attainable  over  a  blast-lamp.  Cool  and 
weigh.  Repeat  until  the  weight  becomes  constant.  The 
expulsion  of  the  sulphuric  acid  can  be  facilitated  by  intro- 
ducing into  the  crucible  a  piece  of  pure  ammonium  car- 
bonate about  the  size  of  a  pea,  covering  the  crucible,, 
and  heating  moderately  until  the  ammonium  carbonate  is 
volatilized,  and  then  strongly,  as  before.  Only  ferric 
oxide  will  be  left.     Calculate  the  per  cent  as  usual. 

Of  the  various  methods  suggested  for  the  determination 
of  iron  volumetrically,  it  is  unnecessary  to  notice  more 
than  two,  namely,  that  turning  upon  the  use  of  potas- 
sium permanganate,  and  that  in  which  potassium  bichro- 
mate is  employed. 

The  first  method,  known  as  Marguerite's,  depends  upon 


42  AMMONIO-FEKKIC    SULPHATE. 

the  fact  that  a  solution  of  potassium  permanganate, 
which  is  intensely  colored,  loses  its  color  when  dropped 
into  a  solution  of  ferrous  oxide,  giving  up  a  portion  of  its 
oxygen,  and  being  decomposed  into  salts  of  manganese 
and  potassium,  until  the  ferrous  is  completely  converted 
into  ferric  oxide.  The  moment  this  conversion  is  complete, 
the  permanganate  imparts  color  to  the  fluid. 

The  analysis  requires  a  standard  solution  of  potassium 
permanganate,  that  is,  one  the  value  of  which  is  known. 

To  prepare  this  solution,  dissolve  6.500  gms.  of  pure 
crystals  of  potassium  permanganate  in  1  litre  of  distilled 
water,  with  frequent  agitation  to  insure  complete  solution, 
if  possible.  After  this,  allow  the  fluid  to  stand  for  24 
hours,  and  siphon  of:  into  another  vessel  the  perfectly 
clear  solution,  and  close  this  tightly  with  a  stopper,  pref- 
erably of  glass. 

There  are  several  methods  of  standardizing  the  solution 
of  potassium  permanganate.  Of  these,  only  two  will  be 
described  as  reliable,  namely,  by  means  of  iron,  or  by  oxalic 
acid.  Of  these,  the  former  (the  method  proposed  by 
Marguerite)  is  the  better  one.  Use  for  the  purpose  fine 
piano-forte  wire,  which  contains  99.7  per  cent  of  iron. 
Dissolve  0.200  gm.  of  the  wire — previously  cleaned  with 
sand-paper  to  remove  oxide,  glaze,  and  dirt — in  a  small 
valved  flask,  with  25  or  30  c.  c.  of  dilute  sulphuric  acid, 
by  the  aid  of  gentle  heat ;  introducing  into  the  flask, 
with  the  wire,  a  small  crystal  of  sodium  carbonate,  about 
as  large  as  a  hemp-seed  ;  by  which  means  the  atmospheric 
air  will  be  displaced  by  carbonic  acid,  thus  preventing 
the  formation  of  ferric  oxide  during  the  solution.  When 
the  iron  is  dissolved,  allow  the  flask  and  contents  to  cool 
slowly.  Do  not  attempt  to  hurry  the  cooling  by  the  ap- 
plication of  any  cold  substance,  as  the  sudden  formation 
of  a  partial  vacuum  may  crush  the  flask  and  scatter  the 
contents. 

A  very  convenient  kind  of  valve  for  the  flask  in  which 
the  iron  wire  is  dissolved  is  the  Kroonig  valve,  described 


FERRIC    OXIDE — VOLUMETRIC.  43 

by  Mohr  in  his  TitrirrnetJiode  (5th  ed.,  1877,  p.  182), 
which  is  made  of  a  piece  of  thick  rubber  tubing,  about 
one  and  a  half  inches  long,  one  end  of  which  is  forced 
over  a  short  glass  tube,  passing  through  the  cork  into 
the  neck  of  the  flask,  while  the  other  end  is  closed  by  a 
short  piece  of  glass  rod.  The  rubber  tube  has  a  longi- 
tudinal slit  cut  in  it  between  the  end  of  the  piece  of  glass 
rod  and  the  glass  tube.  When  the  pressure  is  internal, 
the  slit  opens,  allowing  the  gas  and  vapor  to  escape,  and 
it  closes  when  the  pressure  is  external,  owing  to  the  cool- 
ing of  the  flask,  thus  preventing  the  entrance  of  oxygen. 

When  the  contents  of  the  flask  are  cool,  empty  them 
into  a  large  beaker,  wash  the  flask  well,  adding  the  wash- 
ings to  the  solution,  and  dilute  with  distilled  water  to 
about  700  c.  c.  Then  drop  in  the  solution  of  potassium 
permanganate  to  be  standardized,  slowly,  from  a  Gay- 
Lussac  burette,  w^h  constant  stirring,  until  the  color 
(which  disappears  rapidly  at  first,  and  then  more  gradu- 
ally) finally  becomes  permanent,  and  remains  so  for  one 
minute.  The  final  color  should  be  a  light  pink.  Note 
carefully  the  quantity  of  potassium  permanganate  used, 
and  calculate  the  value  of  1  c.  c.  thus  :  Suppose  19.2  c.  c. 
of  the  permanganate  solution  to  be  sufficient  to  oxidize 
the  solution  of  0.200  gm.  of  iron  wire,  or  0.1994  gm.  of 
pure  metallic  iron  (as  the  wire  is  assumed  to  contain  99.7 
per  cent  of-^the  latter) ;  consequently,  1  c.  c.  of  the  per- 
manganate solution  will  represent  0.01038  gm.  of  metallic 
iron,  or  0.01483  gm.  of  ferric  oxide.  (Fres.,  Quant.,  §112, 
p.  194.)  ,  , 

To  standardize  the  potassium  permanganate  solution  by 
means  of  oxalic  acid,  dissolve  6.300  gms.  of  pure  crystal- 
lized oxalic  acid  in  1  litre  of  water.  Take  50  c.  c.  of  the 
solution,  equivalent  to  0.315  gm.,  and  dilute  with  about 
100  c.  c.  of  water.  Add  6  or  8  c.  c.  pure  concentrated 
sulphuric  acid,  and  heat  to  about  60°  C.  Add  permangan- 
ate solution  from  a  Gray-Lussac  burette,  until  it  imparts 
a  permanent  color,  as  directed  in  the  previous  method. 


44  AMMOTaO-FERRIC   SULPHATE. 

By  comparing  the  equations  representing  the  reactions,  it 
will  be  seen  that  the  same  quantity  of  potassium  perman- 
ganate is  required  to  oxidize  1  molecule  of  oxalic  acid, 
whose  molecular  weight  is  126,  or  2  atoms  of  iron  (in  the 
form  of  monoxide),  whose  molecular  weight  is  112.  Thus, 
the  following  represents  the  oxidation  of  iron, 

10FeSO4+8H2SO4+K2Mn2O8=5Fe3(SO4)3+2MnSO,+K2SO4 

+8H20, 

while  the  next  one  represents  the  oxidation  of  oxalic  acid, 

5(H2C204. 2H20)+3H2SO,+K2Mn208=:  10CO2+2MnSO4+K2 

S04+18H20  ; 

consequently,  126  :  112=0.315  :  0.280.  In  other  words, 
the  0.315  gm.  of  crystallized  oxalic  acid  contained  in  the 
50  c.  c.  of  solution  taken  as  directed  above,  represents 
0.280  gm.  of  metallic  iron ;  and  the  quantity  of  perman- 
ganate solution  required  to  oxidize  0.315  gm.  of  oxalic 
acid  will  oxidize  0.280  gm.  of  metallic  iron.  Suppose  27 
c.  c.  of  the  permanganate  solution  to  be  required  to 
oxidize  the  0.315  gm.  of  oxalic  acid,  then  1  c.  c.  will  be 
equivalent  to  0.01037  gm.  of  metallic  iron,  or  the  result  of 
dividing  0.280  by  27.  The  objection  to  the  use  of  oxalic 
acid  for  standardizing  potassium  permanganate  is  the 
uncertainty  of  procuring  a  perfectly  normal  acid. 

Whichever  method  of  standardizing  the  permanganate 
solution  is  adopted,  it  is  necessary  to  make  more  than  one 
trial.  Should  the  quantities  of  permanganate  required  in 
two  trials  not  differ  by  more  than  one  tenth  of  a  cubic  centi- 
metre, the  average  of  the  two  may  be  taken  as  correct. 
Should  a  greater  difference  than  this  occur,  more  trials 
must  be  made  to  obtain  consistent  results. 

To  determine  the  ferric  oxide,  weigh  about  4  gms.  of 
the  ammonio-ferric  sulphate,  observing  the  precautions 
suggested  before,  transfer  the  substance  to  a  flask  holding 
500  c.  c,  add  about  200  c.  c.  of  warm  water  and  2  or  3  c.  c. 
of  sulphuric  acid.     When  all  is  dissolved,  cool,  and  dilute 


FERRIC   OXIDE — VOLUMETRIC.  45 

with  cool  water  to  the  holding  mark.  Pour  the  solution 
into  a  dry  beaker,  and  stir  well.  Divide  the  fluid  into 
two  equal  portions,  by  filling  a  dry  250  c.  c.  flask  with  a 
portion  of  it,  to  the  holding  mark,  emptying  the  flask 
into  a  reducing  bottle,  washing  the  flask,  and  adding  the 
wash-water  to  the  other.  If  the  flasks  agree,  one  half 
will  have  been  transferred  to  the  bottle  ;  and  that  remain- 
ing in  the  beaker,  together  with  that  adhering  to  the 
larger  flask,  will  compose  the  other  half.  This,  with  the 
washings  of  the  beaker  and  flask,  is  to  be  transferred  to 
another  reducing  bottle  of  similar  size.  Place  in  each  of 
the  bottles  a  piece  of  amalgamated  zinc,  and  a  piece  of 
platinum  foil  about  three  quarters  of  an  inch  wide  and 
four  inches  long,  fill  with  water  to  the  shoulders,  cover 
with  watch-glasses,  and  allow  to  stand  for  24  hours.  A 
strong  current  of  gas  should  be  induced  by  contact 
between  the  zinc  and  platinum.  When  the  foil  is  new,  it 
sometimes  fails  to  produce  the  desired  effect.  In  such  a 
case,  heat  it  in  a  strong  solution  of  potassium  hydrate,  to 
remove  oily  matter ;  scour  the  surface  with  coarse  sand,  to 
roughen  it,  and  wash  it.  Should  the  foil  still  act  badly, 
wet  the  surface  with  a  little  nitro-hydrochloric  acid,  to  re- 
move the  polished  surface,  and  wash  it  with  water.  The 
zinc  used  should  be  amalgamated  ;  otherwise,  as  it  usually 
contains  iron,  in  dissolving,  it  will  impart  iron  to  the  solu- 
tion. Ifc  has  been  found  by  experiment  that  amalgamated 
zinc  will  not  give  up  the  iron  alloyed  with  it,  to  the  solu- 
tion to  be  reduced,  until  nearly,  if  not  quite,  all  the  zinc  is 
dissolved. 

A  very  good  bottle  for  reducing  the  ferric  oxide  is  about 
two  and  a  half  inches  wide,  and  six  inches  high,  with  a 
wide  mouth.  ' 

After  the  ferric  is  reduced  to  ferrous  oxide,  empty  one 
of  the  bottles  into  a  large  beaker,  wash  it  well  with  water, 
adding  the  washings  to  the  solution  ;  add  2  or  3  c.  c.  pure 
sulphuric  acid,  dilute  to  about  700  c.  c,  and  titrate  with 
the  permanganate  solution  in  the  same  manner  as  directed 


46  AMMONIO-FERKIC   SULPHATE. 

for  standardizing.  The  number  of  c.  c.  of  potassium  per- 
manganate used,  multiplied  by  the  standard,  gives  the; 
weight  of  metallic  iron  in  the  solution  treated.  From  this, 
calculate  the  per  cent  of  ferric  oxide. 

The  two  titrations  should  not  differ  more  than  two 
tenths  of  a  c.  c.  If  they  do,  another  determination  should 
be  made. 

The  other  method  of  determining  iron  volumetrically, 
by  the  use  of  potassium  bichromate,  is  preferable  when 
the  iron  is  in  hydrochloric  acid  solution.  The  following 
equation,  6FeCl2+K2Cr207+14HCl=3Fe2Cl6+2KCl+Cr2 
C16+7H20,  shows  that  1  eq.,  or  295.18  parts  of  potassium 
bichromate,  will  convert  6  eq.,  or  336  parts  of  iron,  to  the 
ferric  state.  Then,  if  14.759  gms.  of  potassium  bichromate 
are  dissolved  in  1  litre  of  water,  1  c.  c.  of  the  solution  will 
be  equivalent  to  0. 0168  gm.  of  iron.  Before  using  the  potas- 
sium bichromate,  it  should  be  fused,  and  cooled  under  a 
desiccator.  The  solution  of  bichromate  should  be  stand- 
ardized with  piano-forte  wire,  as  directed  before  for  potas- 
sium permanganate,  dissolving  0.200  gm.  in  30  c.  c.  of 
dilute  hydrochloric  acid.  After  the  solution  is  cool,  pour 
it  into  a  beaker,  dilute,  and  drop  in  from  a  burette  the 
bichromate  solution,  constantly  stirring  with  a  glass  rod. 
The  solution  will  soon  turn  green.  Should  it  turn  brown, 
add  more  hydrochloric  acid.  When  it  becomes  dark 
green,  place  a  drop  on  a  white  plate,  and  combine  it  with 
a  drop  of  solution  of  potassium  ferricyanide,  which  will 
turn  it  blue.  The  solution  of  potassium  ferricyanide 
should  not  be  too  strong,  or  it  will  give  a  red  precipitate. 
As  the  oxidation  by  the  potassium  bichromate  advances, 
the  blue  color  produced  by  the  solution  of  iron  will 
become  faint.  Note  the  number  of  c.  c.  of  bichromate 
solution  used,  and  finish  with  one  only  one  tenth  as  strong. 
When  the  tests  no  longer  produce  a  blue  color,  the  oxida- 
tion is  complete.  From  the  number  of  c.  c.  used  calculate 
what  1  c.  c.  is  equivalent  to. 

For  the  analysis,  reduce  the  hydrochloric  acid  solution 


AMMONIA.  47 

of  the  salt  with  zinc  and  platinum,  as  directed  before, 
titre  with  the  bichromate  solution,  and  from  the  number 
of  c.  c.  used,  and  the  known  value  of  1  c.  c,  calculate  the 
iron. 

For  the  determination  of  the  ammonia,  weigh  about 
1  gm.  of  the  substance,  and  introduce  it  into  a  small  tubu- 
lated retort,  the  tubulure  of  which  is  fitted  with  a  tight 
caoutchouc  stopper,  through  which  passes  a  funnel  tube, 
provided  with  a  stop-cock.  The  kind  called  "  thistle 
tube"  is  the  best.  The  neck  of  the  retort  is  connected 
with  a  piece  of  glass  tube,  of  about  the  same  size,  and 
about  10  inches  long,  by  means  of  a  short  piece  of  large 
rubber  tube,  stretched  over  both,  and  firmly  tied.  The 
glass  tube  is  previously  contracted  by  heat  at  the  end 
nearest  the  retort,  and  filled  with  clean  broken  glass.  The 
other  end  is  fitted  with  a  caoutchouc  stopper,  through 
which  passes  a  small  glass  tube,  turned  down,  so  as  to 
enter  a  small  flask  holding  about  200  c.  c,  and  passing 
through  the  stopper  nearly  to  the  bottom  of  the  flask. 
This  tube  has  blown  on  it  a  large  bulb,  to  prevent  reces- 
sion of  the  fluid  from  the  flask  into  the  retort,  in  case  of 
sudden  contraction  of  the  contents  of  the  latter.  Through 
the  stopper  of  the  flask  also  passes  the  point  of  an 
ordinary  calcium  chloride  tube,  filled  with  broken  glass. 
Connect  the  apparatus,  fasten  the  retort  in  a  holder,  with 
the  neck  inclined  slightly  upward,  at  the  same  time  sup- 
porting the  tube  connected  with  it  and  filled  with  clean 
broken  glass,  and  run  into  the  flask,  through  the  calcium 
chloride  tube,  enough  dilute  hydrochloric  acid,  of  about 
1.050  sp.  gr.  to  slightly  cover  the  point  of  the  tube  con- 
necting the  flask  with  the  retort.  Then  introduce  into  the 
retort,  through  the  funnel  tube,  enough  water  to  dissolve 
the  ammonio-ferric  sulphate.  When  this  is  dissolved, 
run  in  through  the  funnel  tube  20  or  30  c.  c.  of  a  concen- 
trated solution  of  potassium  hydrate,  little  by  little.  Then 
close  the  stop-cock  and  apply  gentle  heat,  gradually  in- 
creasing it,  until  the  fluid  in  the  retort  boils.     Continue 


48  AMMONIO-FERRIC   SULPHATE. 

the  boiling  for  15  or  20  minutes.  When  the  ammonia  is 
expelled,  open  the  stop-cock  of  the  funnel-tube,  and  draw 
a  little  air  through  the  apparatus.  Then  disconnect  it, 
wash  the  tube  connecting  the  flask  with  the  large  tube 
attached  to  the  retort  into  a  small  porcelain  dish,  and  at 
the  same  time  run  water  through  the  calcium  tube  into 
the  flask,  and  pour  the  contents  into  the  dish,  washing  the 
flask  well.  Add  to  the  contents  of  the  dish  an  excess  of 
platinum  tetrachloride,  and  proceed  as  directed  in  the 
analysis  of  potassium  alum.  Great  caution  must  be  exer- 
cised in  igniting  the  ammonium  platino-chloride,  or  loss 
will  be  incurred  by  fine  particles  of  platinum  being  carried 
ofl  by  the  ammonium  chloride.  Rose  directs  that  the 
covered  crucible  be  subjected  to  a  low  heat  for  a  long  time, 
until  the  filter  is  completely  charred,  and  that  then  a 
gradually-increasing  heat  be  applied  to  the  uncovered  cru- 
cible, resting  on  its  side,  with  the  lid  resting  against  the 
mouth.  The  fusion  with  oxalic  acid,  and  the  accompany- 
ing washing,  are  not  required  in  this  case,  as  the  double 
chloride  is  easily  decomposed  and  reduced  to  spongy 
platinum  by  heat  alone.  From  the  weight  of  spongy 
platinum,  calculate  the  per  cent  of  JSTH3. 


Note.—  In  determining  iron  by  Marguerite's  method,  the  presence  of  HC1 
must  be  avoided,  especially  if  the  solution  is  at  all  warm,  since  the  permangan- 
ate under  these  circumstances  will  react  upon  the  HC1,  affording  chlorine.  Thus  : 
KaMn908  +  16HC1  =  3KC1  +  2MnCla  +  8H,0  +  10C1. 

Some  of  the  chlorine  may  convert  the  ferrous  salt  present  into  the  ferric,  but 
some  will  usually  escape,  and  the  results  obtained  will  consequently  be  higher 
than  the  truth. 


CHAPTER    X. 

FELDSPAR. 

The  following  analyses,  taken  from  Dana's  Mineralogy 
show  the  composition  of  ordinary  feldspar  : 

Orthoclase.        Albite. 

Silica 64.25  65.46 

Alumina 18.80  20.74 

Ferrous  Oxide 0.54 

Lime < 1.20  0.71 

Magnesia 0.74 

Soda 2. 40  9. 98 

Potash 12.44  1.80 

Loss  by  ignition 0. 30  

99.39  99.97 

Pulverize  3  or  4  gms.  of  the  feldspar  very  line,  in  an 
agate  mortar,  and  keep  the  powder  in  a  small,  corked 
bottle.  Fuse  over  a  blast-lamp  1  gm.  of  this,  carefully 
weighed,  in  a  2-oz.  platinum  crucible,  intimately  mixed 
with  about  5  gms.  of  flux,  composed  of  equal  parts  of 
potassium  and  sodium  carbonates.  The  combined  car- 
bonates make  a  much  more  fusible  flux  than  either  alone. 
Examine  the  crucible  occasionally,  and,  when  the  contents 
are  fused  so  to  flow  when  the  crucible  is  inclined,  move 
it  about,  after  laying  the  cover  aside  in  a  convenient  place, 
in  such  a  way  as  to  cause  the  contents  to  coat  the  sides, 
instead  of  cooling  in  a  solid  mass  at  the  bottom,  and  dip 
it,  while  still  hot,  into  a  beaker  of  cold  water,  to  about 
half  of  its  depth.  Hold  it  in  the  water  for  a  few  seconds, 
remove  it,  and,  after  the  lapse  of  a  few  more  seconds,  dip 
it  again.  Repeat  this  treatment  until  the  crucible  and 
contents  are  cool  enough  to  immerse  without  spattering. 
Then  lay  the  crucible  on  its  side  in  the  beaker,  which 
should  be  just  large  enough  to  permit  this,  and  have  in  it 


50  FELDSPAR. 

a  sufficient  quantity  of  water  barely  to  cover  the  crucible. 
Then  put  the  lid  also  in  the  beaker,  and,  after  placing  a 
convex  glass  over  it,  allow  it  to  stand  until  the  fused  mass 
is  sufficiently  softened  to  be  removed  from  the  crucible. 
Owing  to  the  contraction  and  expansion  caused  by  this 
treatment,  the  mass  can  frequently  be  removed  at  once 
from  the  crucible  in  thin  cakes.     The  object  of  using  as 
small  a  beaker  and  as  little  water  as  possible  is  to  avoid 
the  evaporation,  afterward,  of  an  unnecessary  quantity  of 
fluid.     Should  the'  contents  of  the  crucible  be  difficult  to  re- 
move in  this  way,  the  operation  may  be  hastened  by  digest- 
ing on  a  water-bath,  occasionally  moving  the  crucible  with 
a  glass  rod,  and  replacing  the  water  lost  by  evaporation. 
Under  no  circumstances  should  an  effort  be  made  to  re- 
move the  mass  by  force,  as  in  doing  so  there  is  great 
danger  of  injuring  the  crucible.     After  removing  the  sub- 
stance from  the  crucible,  place  the  latter,  with  the  cover, 
in  another  vessel,  pour  on  them  a  little  dilute  hydrochloric 
acid,  to  dissolve  any  adhering  particles,  and  wash  them 
with  water.     Pour  this  solution  cautiously  into  the  vessel 
containing  the  fused  feldspar,  keeping  it  covered  with  a 
glass,   to  prevent  loss  by  effervescence,   and  add  more 
hydrochloric  acid,  if  necessary,  a  little  at  a  time.     When 
the  fluid  is  acid,   heat  until  all    carbonic   acid   is   ex- 
pelled.    Then,  if    the  mineral    is    entirely  decomposed, 
transfer  all  to  a  casserole,  and  evaporate  on  a  water-bath 
to  dryness.     Then  heat  in  an  air-bath  at  a  temperature  of 
from  100°  to  110°  C.  until  the  odor  of  hydrochloric  acid 
disappears.     Should  there  be  any  undecomposed  mineral, 
allow  it  to  settle,  decant  the  clear  fluid  into  a  casserole, 
and  begin  to  evaporate  it  as  above.     In  the  mean  time,  add 
some  strong  hydrochloric  acid  to  the  residue,  and  heat  to 
dissolve  it  if  possible.     Should  it  dissolve,  add  the  solution 
to  the  first  one.     Should  it  not  dissolve,  dilute  with  a 
little  water,  filter,  wash,  and  add  the  filtrate  to  the  prin- 
cipal solution.     Dry  the  insoluble  residue,  burn  it  with 
the  filter  in  a  platinum  crucible,  fuse  it  with  about  five 


SILICA  AND   ALUMINA.  51 

times  its  weight  of  mixed  carbonates,  as  in  the  first  case, 
and  treat  as  directed  above.  Repeat  the  treatment  until 
the  feldspar  is  all  decomposed.  Undecomposed  mineral 
can  be  detected  by  the  rapidity  with  which  it  settles  to 
the  bottom  of  the  fluid,  and  by  feeling  hard  and  gritty 
when  pressed  by  a  glass  rod,  while  separated  silica  rises 
readily  in  the  solution  when  agitated,  settles  slowly,  and 
offers  no  resistance  to  the  rod.  After  the  mass  is  thor- 
oughly dried,  moisten  it  with  20  c.  c.  dilute  hydrochloric 
acid,  heat  at  a  temperature  just  below  boiling  for  20  or  30 
minutes,  and  dilute  with  50  c.  c.  hot  water ;  every  thing 
should  now  be  in  solution  except  the  silica.  Now  filter 
out  the  silica,  wash  it  with  hot  water  until  the  washings 
give  no  reaction  for  chlorine,  when  treated  with  silver 
nitrate,  and  dry  the  precipitate  on  the  filter,  at  a  temper- 
ature of  from  100°  to  110°  C.  When  the  silica  is  perfectly 
dry,  invert  the  filter  in  a  weighed  platinum  crucible,  stand- 
ing on  a  sheet  of  glazed  paper,  roll  the  filter  gently 
between  the  fingers  in  such  a  way  as  to  remove  the  con- 
tents from  the  paper  to  the  crucible,  and,  without  lifting 
the  filter  from  the  crucible,  fold  it  and  press  it  carefully 
down  upon  the  silica.  After  brushing  into  the  crucible 
any  particles  that  may  have  fallen  on  the  paper,  put  on  the 
cover,  and  ignite  at  first  at  a  heat  not  more  than  sufficient 
to  char  the  paper.  Continue  the  low  heat  as  long  as 
smoke  emerges  from  the  crucible.  After  all  volatile 
matter  has  been  expelled,  incline  the  crucible  on  the  sup- 
port, and  gradually  raise  the  heat  to  the  highest  point 
attainable  by  means  of  a  good  burner,  keeping  the  cover 
on  for  a  few  minutes.  Finally,  remove  the  cover,  and  con- 
tinue heating  until  the  carbon  of  the  filter  is  consumed 
and  the  silica  is  white.  Then  cool  the  crucible  and  con- 
tents in  a  desiccator,  weigh,  and  calculate  the  per  cent  of 
silica,  which  still  retains,  perhaps,  a  little  alumina.  After 
weighing,  moisten  the  contents  of  the  crucible  with  pure 
concentrated  sulphuric  acid,  add  about  1  gm.  of  ammonium 
fluoride,  which  leaves  no  residue  after  ignition,  incline  the 


52  FELDSPAR. 

crucible  on  the  support,  replace  the  cover,  and  apply  the 
heat  of  a  burner  in  such  a  way  that  the  flame  will  strike 
the  edge  of  the  crucible  and  lid.  When  the  sulphuric 
acid  is  expelled,  heat  the  whole  crucible  strongly,  cool,  and 
weigh  it.  Repeat  this  treatment  until  the  crucible  ceases 
to  lose  weight.  The  loss  represents  silica  expelled  as 
silicon  fluoride.  If  any  thing  remains  in  the  crucible, 
fuse  it  with  a  little  acid  potassium,  or  sodium  sulphate, 
cool,  moisten  with  sulphuric  acid,  and  heat  again,  until 
the  mass  becomes  fluid.  Finally,  cool  and  dissolve  in 
water,  and  add  the  solution  to  the  filtrate  from  the  silica. 

Rapid  ignition  in  the  first  instance,  will  cause  loss  of 
silica,  as  its  particles,  being  very  minute  and  light,  are 
liable  to  be  carried  off  by  the  gases  expelled  from  the 
filter-paper  by  combustion,  and  also  by  the  vapor  of  the 
water  remaining  in  the  silica  itself  after  drying,  since  all 
moisture  can  not  be  expelled  from  it  by  drying  at  a 
temperature  which  will  not  destroy  the  fibre  of  the  filter. 

To  determine  the  alumina,  add  to  the  filtrate  from  the 
silica,  ammonia  until  the  fluid  is  slightly  alkaline,  and  pro- 
ceed as  directed  in  the  analysis  of  potassium  alum. 

If  there  be  any  oxide  of  iron  in  the  feldspar,  it  will  be 
found  in  the  precipitate  of  alumina,  in  which  case  fuse 
the  ignited  precipitate  with  pure  potassium  hydrate,  pre- 
ferably in  a  silver  crucible,  digest  the  fused  mass  until  it 
is  reduced  to  a  pulverized  form,  and  entirely  removed 
from  the  crucible,  which  is  to  be  washed  and  removed. 
Digest  again,  until  the  alumina  is  dissolved  in  the  alkaline 
fluid,  and  only  ferric  hydrate  remains.  Filter,  wash  well, 
dry,  ignite,  and  weigh  the  ferric  oxide.  Its  weight,  de- 
ducted from  the  known  weight  of  alumina  and  ferric 
oxide  combined,  gives  the  weight  of  the  alumina  ;  or  the 
alumina  may  be  determined  directly  by  acidifying  the 
alkaline  solution  with  hydrochloric  acid,  then  making  it 
alkaline  with  ammonia,  boiling,  and  determining  the 
alumina  as  before,  as  directed  in  the  analysis  of  potas- 
sium alum. 


FERRIC    OXIDE — ALKALIES.  53 

To  determine  the  ferric  oxide  by  titration,  fuse  the 
ignited  precipitate  of  alumina  containing  ferric  oxide, 
with  6  or  8  times  its  weight  of  acid  potassium  sulphate, 
until  the  second  molecule  of  sulphuric  acid  is  expelled  ; 
cool,  add  a  volume  of  pure  concentrated  sulphuric  acid 
equal  to  that  of  the  fused  mass,  heat  again  carefully, 
until  the  contents  of  the  crucible  become  fluid.  Then 
cool,  place  the  crucible  in  a  vessel  of  hot  water,  and  digest 
over  heat  until  the  sulphates  are  dissolved.  Then  reduce 
with  zinc  and  platinum,  and  titrate  with  potassium  per- 
manganate, as  directed  in  the  analysis  of  ammonio-ferric 
sulphate,  and  calculate  the  per  cent  of  ferric  oxide.  If 
this  method  is  adopted,  the  alumina  is,  of  course,  to  be 
determined  by  difference. 

To  determine  the  lime  and  magnesia,  treat  the  filtrate 
from  the  precipitate  of  alumina  and  ferric  oxide  as 
directed  in  the  analysis  of  limestone. 

The  best  method  of  determining  the  sodium  and  potas- 
sium is  that  of  Professor  J.  Lawrence  Smith  (Am.  Jour. 
Sci.  and  Arts,  Yol.  I.,  1871,  p.  269)  for  separating  the 
alkalies  from  silicates.  The  method  is  described  in  his 
own  words  :  "The  silicate  is  to  be  well  pulverized  in  an 
agate  mortar  ;  for  the  analysis  I  take  i  gm.  or  1  gm. ;  the 
former  is  most  commonly  used,  as  being  sufficient,  and 
best  manipulated  in  the  crucible  used ;  a  gramme, 
however,  may  be  conveniently  employed.  The  weighed 
mineral  is  placed  in  a  large  agate  mortar,  or,  better,  in  a 
glazed  porcelain  mortar,  of  %  to  1  pint  capacity.  Weigh 
out  an  equal  quantity  of  granular  sal-ammoniac  (a  centi- 
gramme more  or  less  is  of  no  consequence),  put  it  in  the 
mortar  with  the  mineral,  rub  the  two  together  intimately  ; 
after  which,  add  8  parts  of  carbonate  of  lime,  in  three  or 
four  portions,  and  mix  intimately  after  each  addition  ; 
empty  the  contents  of  the  mortar  completely  upon  a  piece 
of  glazed  paper,  that  ought  always  to  be  under  the 
mortar,  and  introduce  into  the  crucible.  The  crucible  is 
tapped  gently  upon  the  table  and  the  contents  settled  down. 


54  FELDSPAR. 

"It  is  then  clasped  by  a  metallic  clamp  in  an  inclined 
position,  or  it  is  placed  in  the  support  referred  to  in  the 
latter  part  of  this  article,  leaving  outside  about  J  or  f 
inch  ;  a  small  Bunsen  burner  is  now  placed  beneath  the 
crucible,  and  the  heat  brought  to  bear  just  about  the  top 
of  the  mixture,  and  gradually  carried  toward  the  lower 
part,  until  the  sal-ammoniac  is  completely  decomposed, 
which  takes  about  4  or  5  minutes  ;  heat  is  then  applied  in 
the  manner  suggested,  either  with  the  blast  or  with  the 
burner  referred  to,  acting  by  its  own  draught,  and  the 
whole  kept  up  to  a  bright  red  heat  for  about  from  40  to  60 
n^nutes.  It  is  well  to  avoid  too  intense  a  heat,  as  it  may 
vitrify  the  mass  too  much.  The  crucible  is  now  allowed 
to  cool,  and  when  cold,  the  contents  will  be  found  to  be 
more  or  less  agglomerated,  in  the  form  of  a  semi-fused 
mass.  A  glass  rod,  or  blunt  steel  point,  will  most  com- 
monly detach  the  mass,  which  is  to  be  dropped  into  a 
platinum  or  porcelain  capsule,  of  about  150  c.  c.  capacity, 
and  60  or  80  c.  c.  of  distilled  water  is  added.  In  the  course 
of  a  longer  or  shorter  space  of  time,  the  mass  will  slake 
and  crumble  after  the  manner  of  lime ;  still  better,  this 
may  be  hastened  by  bringing  the  contents  of  the  capsule 
to  the  boiling-point,  either  over  a  lamp  or  water-bath.  At 
the  same  time,  water  is  put  into  the  crucible,  to  slake  out 
any  small  particles  that  may  adhere  to  it,  and,  subse- 
quently, this  is  added  to  that  in  the  capsule,  washing  off 
the  cover  of  the  crucible  also. 

' '  After  the  mass  is  completely  slaked,  the  analysis  may 
be  proceeded  with,  although,  as  a  general  thing,  I  prefer 
to  allow  the  digestion  to  continue  6  or  8  hours,  which,  how- 
ever, is  not  necessary.  If  the  contents  of  the  crucible  are 
not  easily  detached,  do  not  use  unnecessary  force,  as  the 
crucible  may  be  injured  by  it,  but  fill  the  crucible  to 
about  two  thirds  of  its  capacity  with  water,  bring  almost 
to  the  boiling-point,  and  lay  it  in  the  capsule,  with  the 
upper  portion  resting  on  the  edge  ;  the  lime  will  slake  in 
the    crucible,    and    then    may  be    washed    thoroughly 


ALKALIES.  55 

into    the     dish,     and,    as  before,     the    cover   is    to    be 
washed  off. 

"  We  have  now,  by  this  treatment  with  water,  the  ex- 
cess of  lime  slaked  into  a  hydrate,  and  some  of  the  lime, 
combined  with  the  silica  and  other  ingredients  of  the  sili- 
cate, in  an  impalpable  form ;  in  solution  there  is  the  excess 
of  the  chloride  of  calcium  formed  in  the  operation,  and 
all  the  alkalies  originally  contained  in  the  mineral  as 
chlorides,  and  all  that  now  remains  to  be  done  is  to  filter, 
separate  the  lime  as  carbonate,  and  we  have  nothing  left 
but  the  chlorides  of  the  alkalies.  To  do  this  I  proceed  as 
follows : 

"  Throw  the  contents  of  the  capsule  on  a  filter  (the  size 
preferred  for  the  quantity  above  specified  is  one  3  to  3J 
inches  in  diameter),  wash  well,  to  do  which  requires  about 
200  c.  c.  of  water  ;  the  washing  is  executed  rapidly.  The 
contents  of  the  filter  (except  in  those  cases  where  the 
amount  of  the  mineral  is  very  small,  and  there  is  no  more 
for  the  estimation  of  the  other  constituents)  is  of  no  use, 
unless  it  be  desired  to  heat  again,  first  adding  a  little  sal- 
ammoniac  to  see  if  any  alkali  still  remains  in  it,  a  precau- 
tion I  find  unnecessary.  The  filtrate  contains,  in  solution, 
all  the  alkalies  of  the  mineral,  together  with  some  chloride 
of  calcium  and  caustic  lime  ;  to  this  solution,  after  it  has 
been  placed  in  a  platinum  or  porcelain  capsule,  is  added  a 
solution  of  pure  carbonate  of  ammonia  (equal  to  about  1^ 
gms.  is  required).  This  precipitates  all  the  lime  as  car- 
bonate ;  it  is  not,  however,  filtered  immediately,  but  is 
evaporated  over  a  water-bath,  to  about  40  c.  c,  and  to 
this  we  add  again  a  little  carbonate  of  ammonia,  and  a 
few  drops  of  caustic  ammonia,  to  precipitate  a  little  lime 
that  is  re-dissolved  by  the  action  of  the  sal-a-mmoniac  on 
the  carbonate  of  lime.  Filter  on  a  small  filter  (2  inches), 
which  is  readily  and  thoroughly  washed  with  but  a  little 
water,  and  the  filtrate  allowed  to  run  into  a  small  beaker 
glass.  In  this  filtrate  are  all  the  alkalies  as  chlorides,  and 
a  little  sal-ammoniac  ;  add  a  drop  of  a  solution  of  carbon- 


56  FELDSPAR. 

ate  of  ammonia,  to  make  sure  that  no  lime  is  present. 
Evaporate  over  a  water -bath  in  a  tared  platinum  dish,  in 
which  the  alkalies  are  to  be  weighed ;  the  capsule  used  is 
about  from  30  to  60  c.  c.  capacity,  and  during  the  evapora- 
tion is  never  filled  to  more  than  two  thirds  its  capacity. 
After  the  filtrate  has  been  evaporated  over  the  water- 
bath  to  dryness,  the  bottom  of  the  dish  is  dried,  and,  on  a 
proper  support,  heated  very  gently,  by  a  Bunsen  flame,  to 
drive  off  the  little  sal-ammoniac.  It  is  well  to  cover  the 
ca/psule  with  a  piece  of  thin  platinum,  to  prevent  any 
possible  loss  by  the  spitting  of  the  salt  after  the  sal-am- 
moniac has  been  driven  off.  Gradually  increasing  the 
heat,  the  temperature  of  the  dish  is  brought  up  to  a  point 
a  little  below  redness,  the  cover  being  off  (the  cover  can  be 
cleansed  from  any  sal-ammoniac  that  may  have  condensed 
by  heating  it  over  the  lamp).  The  capsule  is  again 
covered,  and  when  sufficiently  cooled,  before  becoming 
fully  cold,  is  placed  on  the  balance  and  weighed.  This 
weight  gives,  as  chlorides,  the  amount  of  alkalies  contained 
in  the  mineral.  If  chloride  of  lithium  be  present,  it  is 
necessary  to  weigh  quickly ;  for  this  salt,  being  very  de- 
liquescent, attracts  moisure  rapidly.  It  not  unfrequently 
occurs  that  the  chlorides,  at  the  end  of  the  analysis,  are 
more  or  less  colored  with  a  small  quantity  of  carbon, 
arising  from  certain  constituents  in  carbonate  of  am- 
monia ;  the  quantity  is  usually  very  minute,  and  in  no 
way  affects  the  accuracy  of  the  analysis.  In  selecting 
pure  carbonate  of  ammonia  for  analytical  purposes,  it  is 
well  to  select  specimens  that  are  not  colored  by  the  action 
of  light.  It  only  now  remains  to  separate  the  alkalies  by 
the  known  methods." 

The  crucible  and  burner  employed  by  Professor  Smith 
in  separating  the  alkalies  from  silicates  are  of  his  own  de- 
vising, and  excellent  for  the  purpose.  A  description  and 
drawing  of  them  will  be  found  in  Crooke' s  Select  Methods \ 
p.  409,  in  the  chapter  on  decomposition  of  silicates. 

To  separate  the  sodium  and  potassium  and  determine 


ALKALIES — LITHIUM.  5? 

them,  dissolve  the  combined  chlorides  (after  weighing 
them)  in  20  or  30  c.  c.  of  warm  water.  Should  the  solu- 
tion be  complete,  transfer  the  solution  to  a  small  porcelain 
dish>  add  3  or  4  drops  of  hydrochloric  acid,  and  as  much 
solution  of  platinum  tetrachloride  as  contains  an  amount 
of  the  salt  equivalent  in  weight  to  four  times  that  of  the 
combined  chlorides  present,  and  determine  the  potassium 
as  directed  in  the  analysis  of  potassium  alum.  Should 
the  combined  chlorides  not  go  completely  into  water  solu- 
tion, filter,  evaporate  the  filtrate  'in  a  platinum  dish  as 
before,  and  proceed  as  directed  above.  The  solution  in 
water  must  be  complete.  Any  insoluble  residue  can  not  be 
alkaline  chloride,  and  as  the  sodium  is  estimated  by  dif- 
ference, it  would  falsify  the  results.  Deduct  the  weight 
of  potassium  found,  calculated  to  potassium  chloride, 
from  the  weight  of  the  combined  chlorides.  The  differ- 
ence will  be  sodium  chloride.  Calculate  the  per  cent  of 
K20  and  Na20. 

Ignite  1  gm.  of  feldspar,  and  from  loss  calculate  per  cent 
of  moisture  and  organic  matter. 

Lithium  is  sometimes  found  in  feldspar.  When  such  is 
the  case,  it  is  to  be  looked  for  in  the  solution  of  the  alka- 
line chlorides. 

Make  the  solution  slightly  acid,  evaporate  to  dryness  at 
120°  C,  add  a  mixture  of  equal  parts  of  absolute  alcohol 
and  anhydrous  ether,  wash  into  a  flask  with  the  same, 
digest  for  24  hours,  shaking  occasionally,  decant  on  a 
filter,  and  treat  with  smaller  quantities  of  the  mixture  of 
alcohol  and  ether.  Finally,  wash  on  the  filter,  with  the 
same  mixture,  until  the  residue  gives  no  evidence  of  the 
presence  of  lithium  before  the  spectroscope.  (Pogg.  An- 
nal,  66,  79.) 

As  some  sodium  and  potassium  chlorides  may  be  dis- 
solved with  the  lithium  chloride,  evaporate  off  the  alcohol 
and  ether  at  low  heat,  just  to  dryness,  and  treat  the  im- 
pure lithium  chloride  in  the  same  way.  Should  any  res- 
idue of  sodium  and  potassium  chloride  be  left  undis- 


58  FELDSPAR. 

solved,  filter  it  out,  and  add  it  to  the  first  one.  To  the 
alcoholic  solution  add  20  or  30  c.  c.  of  water,  and  boil  out 
the  alcohol  and  ether,  add  to  the  solution  a  sufficient 
quantity  of  pure  sodium  phosphate,  and  enough  pure 
sodium  hydrate  to  keep  the  reaction  alkaline,  and 
evaporate  the  mixture  to  dryness ;  pour  water  over  the 
residue,  in  sufficient  quantity  to  dissolve  the  soluble  salts 
with  the  aid  of  a  gentle  heat,  add  an  equal  volume  of  am- 
monia, digest  at  a  gentle  heat,  filter  after  12  hours,  and 
wash  the  basic  phosphate  of  lithia  with  a  mixture  of  equal 
volumes  of  water  and  ammonia.  Evaporate  the  filtrate 
and  washings  to  dryness,  and  treat  the  residue  in  the  same 
way  as  before.  Should  any  more  lithium  phosphate  be 
obtained,  add  this  to  the  principal  quantity.  Dry  the  pre- 
cipitate, brush  it  from  the  filter  as  perfectly  as  possible 
into  a  clock-glass,  burn  the  filter  in  a  weighed  crucible, 
add  the  precipitate,  and  ignite  again,  at  a  moderate  red 
heat.  Cool  and  weigh  the  basic  lithium  phosphate  (Li3 
P04). 

Dissolve  the  residue  of  sodium  and  potassium  chlorides 
in  water,  and  treat  as  before  for  the  determination  of 
sodium  and  potassium,  when  no  lithium  is  present. 


CHAPTER  XL 

LIMESTONE. 

The  stone  may  contain  lime,  magnesia,  iron,  alumina, 
•silica,  carbonic  acid,  sulphur,  phosphoric  acid,  water,  and 
organic  matter,  also  manganese,  chlorine,  fluorine,  alkalies, 
and  even  other  constituents  in  minute  quantities.  The 
lime  may  exist  as  carbonate  or  sulphate,  the  magnesia  as 
carbonate  or  silicate,  the  iron  as  sulphide  (pyrites)  or 
oxide,  and  the  silica  as  quartz  or  as  silicic  acid  combined 
with  bases. 

The  more  common  constituents,  and  those  required  to 
Ibe  determined  for  technical  purposes,  are  lime,  magnesia, 
alumina,  iron,  silica,  carbonic  acid,  phosphoric  acid, 
and  sulphur. 

For  an  analysis  of  this  character,  dry  a  few  gms.  of  the 
finely  pulverized  stone,  to  constant  weight  at  150°  C,  and 
keep  it  in  a  stoppered  bottle.  Weigh  1  gm.  of  the  dry 
powder,  transfer  it  to  a  small  beaker,  add  20  c.  c.  of  water, 
«over  the  beaker  with  a  convex  glass,  add  5  c.  c.  of  con- 
centrated hydrochloric  acid,  1  c.  c.  of  concentrated  nitric 
acid,  and  heat  slowly  to  boiling.  Filter,  and  wash  with 
30  or  40  c.  c.  of  hot  water,  and  proceed  at  once  to  evapo- 
rate the  filtrate  and  washings  over  a  water-bath.  Dry  the 
filter  and  any  undissolved  residue,  ignite  them  in  a  small 
platinum  crucible  juntil  the  carbon  of  the  filter  is  entirely 
consumed,  add  1  or  2  gms.  sodium  carbonate,  and  0.100 
gm.  sodium  nitrate,  and  fuse  until  the  contents  of  the 
crucible  are  fluid.  Remove  the  fused  mass  from  the  cru- 
cible with  water,  dissolve  off  any  adhering  particles  with 
hydrochloric  acid,  and  add  the  solution  to  the  vessel  con- 
taining the  principal  contents  of  the  crucible,  keeping  it 
covered  to  avoid  loss  by  effervescence,  also  adding  more 


60  LIMESTONE. 

hydrochloric  acid  if  necessary  to  render  the  solution  acid. 
Boil  out  free  carbonic  acid,  and  combine  with  the  principal 
solution  on  the  water-bath.  Evaporate  all  to  dryness, 
transfer  to  an  air-bath,  and  heat  at  a  temperature  of  about 
110°  C.  until  the  odor  of  hydrochloric  acid  disappears. 
Then  add  1  c.  c.  of  concentrated  hydrochloric  acid,  and  20 
c.  c.  of  water,  heat  to  incipient  boiling,  dilute  with  50  c.  c. 
of  water,  filter,  and  wash  with  hot  water,  until  the  wash- 
ings show  no  turbidity  when  treated  with  silver  nitrate 
(using  only  2  or  3  drops  of  the  wash- water  at  a  time,  and 
not  beginning  to  test  until  40  or  50  c.  c.  of  it  have  passed 
through  the  filter).  Dry  the  funnel  and  contents  in  an 
air-bath,  at  a  temperature  of  about  110°  C,  ignite  in  a 
weighed  crucible  (observing  the  precautions  given  in  the 
analysis  of  feldspar),  cool,  and  weigh  the  silica. 

To  the  filtrate  from  the  silica,  add  ammonia  to  alkaline 
reaction,  to  precipitate  the  aluminum  and  ferric  hydrates, 
boil  out  excess  of  ammonia,  allow  the  precipitate  to  settle, 
decant  the  clear  fluid  on  a  filter,  and,  as  some  lime  and 
magnesia  may  be  carried  down  by  the  precipitat,e  of 
hydrates,  dissolve  it  in  the  beaker,  with  as  little  dilute 
hydrochloric  acid  as  possible,  ~re-precipitate  by  adding  a 
slight  excess  of  ammonia,  and  boiling  as  before.  Filter, 
wash,  dry,  and  weigh  the  alumina  and  ferric  oxide 
together.  Consult  analysis  of  potassium  alum,  and  that 
of  ammonia-iron-alum. 

If  it  be  desired  to  determine  the  alumina  and  ferric  oxide 
separately,  proceed  as  directed  in  the  analysis  of  feldspar. 

Should  the  filtrate  and  washings  from  the  hydrates  ex- 
ceed 100  c.  c,  concentrate  to  that  bulk,  if  possible,  and 
add  1  c.  c.  of  ammonia.  If  the  ammonia  produce  a  pre- 
cipitate other  than  aluminum  or  ferric  hydrate,  acidify  the 
solution  with  hydrochloric  acid,  boil  for  a  minute,  and 
then  make  it  alkaline  again  with  ammonia.  This  is  done 
to  introduce  a  sufficient  amount  of  ammonium  chloride  to 
prevent  the  precipitation  of  magnesium  hydrate.  Then 
add  40  c.   c.    of  a  solution  of   ammonium  oxalate   (pre- 


LIME — MAGNESIA.  61 

pared  by  dissolving  1  part  of  the  oxalate  in  24  parts  of 
water),  enough  to  precipitate  all  the  lime  as  oxalate,  and 
convert  the  magnesia  also  into  oxalate,  which  remains  in 
solution.  Fresenius  says  this  excess  is  absolutely  indis- 
pensable to  insure  complete  precipitation  of  the  lime,  as 
calcium  oxalate  is  slightly  soluble  in  magnesium  chloride, 
not  mixed  with  ammonium  oxalate.  (See  his  Experiment 
No.  92,  p.  600.)  After  adding  the  ammonium  oxalate, 
heat  just  to  boiling  and  allow  the  fluid  to  stand  undis- 
turbed for  some  time.  After  the  precipitate  has  settled 
perfectly,  decant  the  clear  fluid  through  a  filter,  wash  by 
decantation  once  with  about  25  c.  c.  of  hot  water,  and 
set  this  filtrate  aside  as  filtrate  No.  1.  Then  dissolve  the 
precipitate  of  calcium  oxalate  (mixed  with  a  little  mag- 
nesium oxalate)  in  the  beaker,  with  as  little  hot  dilute 
hydrochloric  acid  as  possible.  Should  any  of  the  precipi- 
tate have  passed  over  on  the  filter,  wash  it  back  into  the 
acid  solution,  dilute,  if  necessary,  to  about  50  c.  c.  with 
hot  water,  make  alkaline  with  ammonia,  add  5  or  6  c.  c. 
of  ammonium  oxalate  solution,  stir,  and  allow  the  precipi- 
tate to  settle.  When  it  has  perfectly  subsided,  filter 
through  the  previous  filter,  transfer  the  precipitace  to  the 
same,  wash  it  thoroughly  with  hot  water,  and  determine 
the  lime  as  directed  in  the  analysis  of  calcium  carbonate. 

The  first  filtrate  contains  the  larger  portion  of  the  mag- 
nesia, and  the  second  the  remainder.  (See  Fres.,  Experi- 
ment No.  93,  p.  600.)  Acidify  the  second  filtrate  and  wash- 
ings with  hydrochloric  acid,  concentrate  to  small  bulk,  and 
add  it  to  the  first.  Do  not  attempt  to  concentrate  the  first 
filtrate. 

To  determine  the  magnesia,  make  the  combined  filtrates 
from  the  calcium  oxalate  alkaline  with  ammonia,  if  not 
already  so,  add  30  c.  c.  of  the  ordinary  solution  of  hydro- 
disodium  phosphate,  and  determine  the  magnesia  as 
directed  in  the  analysis  of  magnesium  sulphate. 

To  insure  the  recovery  of  all  the  magnesium,  either 
evaporate  the  filtrate  from  the  magnesium  phosphate  to 


62  LIMESTONE. 

dryness,  in  a  platinum  dish,  bnrn  ont  the  ammonium 
chloride,  dissolve  the  residue  in  water  containing  a  few 
drops  of  hydrochloric  acid,  and  proceed  as  in  the  first  in- 
stance ;  or,  concentrate  to  small  volume,  add  4  or  5  c.  c. 
strong  nitric  acid,  evaporate  to  dryness,  add  4  or  5  c.  c. 
strong  hydrochloric  acid,  evaporate  nearly  dry,  dissolve 
in  water,  and  determine  magnesium  as  before. 

(See  J.  Lawrence  Smith,  in  Am.  Chem.,  Yol.  III.,  p.  201.) 

Determine  the  carbonic  acid  by  one  of  the  methods 
given  in  analysis  of  calcite ;  or,  if  the  stone  contains  no 
organic  matter,  fuse  4  gms.  vitrified  borax  in  a  platinum 
crucible,  cool  and  weigh,  then  transfer  1  gm.  of  pulverized 
and  well-dried  stone  to  the  crucible,  and  weigh  again. 
Then  heat  gradually  to  redness,  and  continue  until  all  is 
fused ;  cool  and  weigh.  The  loss  of  weight  is  carbonic 
acid.     (SeeFres.,  §139.) 

To  determine  the  sulphur,  dissolve  5  gms.  in  a  mixture 
of  15  c.  c.  of  strong  hydrochloric  acid,  5  c.  c.  of  strong 
nitric  acid,  and  10  c.  c.  of  water,  in  a  covered  casserole, 
heat  to  boiling,  and  when  effervescence  ceases,  remove  the 
cover,  add  10  c.  c.  strong  hydrochloric  acid,  and  evaporate 
to  dryness  to  expel  nitric  acid.  Then  add  to  the  dry  mass 
1  c.  c.  of  concentrated  hydrochloric  acid  and  50  c.  c.  of 
water,  and  heat  just  to  boiling.  Filter  out  any  residue, 
and  wash  with  about  50  c.  c.  of  hot  water.  Nearly  neu- 
tralize the  nitrate  with  ammonia,  add  2  c.  c.  of  barium 
chloride  solution  (containing  1  part  of  the  salt  in  10 
parts  of  water),  treat  the  precipitate  of  barium  sulphate 
as  in  the  analysis  of  magnesium  sulphate,  and  calculate 
the  sulphur. 

To  determine  the  phosphoric  acid,  dissolve  5  gms.  of  the 
stone  in  10  c.  c.  of  strong  nitric  acid,  and  30  c.  c.  of  hot  water, 
in  a  casserole  covered  with  a  convex  glass.  When  effer 
vescence  ceases,  remove  the  cover,  and  evaporate  to  dry- 
ness. To  the  dry  mass  add  5  c.  c.  of  strong  nitric  acid, 
and  50  c.  c.  of  water,  and  boil.  Then  filter,  wash  with 
about  50  c.  c.  of  water,  nearly  neutralize  with  ammonia. 


WATER — ORGANIC  MATTER.  63 

add  25  c.  c.  of  molybdic  acid  solution,  and  allow  to  stand 
for  some  hoars  in  a  warm  place.  Should  a  yellow  precip- 
itate appear,  filter  it  out,  and  wash  it  with  molybdic  acid 
solution  (diluted  with  an  equal  volume  of  water).  Dis- 
solve the  precipitate  through  the  filter  into  a  small  beaker 
with  the  smallest  possible  amount  of  dilute  ammonia,  add 
2  c.  c.  of  magnesium  mixture,  and  proceed  as  directed  in 
the  analysis  of  hydro-disodium-phosphate.  Should  a 
second  precipitate  appear  in  the  filtrate  from  the  first  pre- 
cipitate of  phospho-molybdate,  filter  it  out  and  treat  it  in 
the  same  way.  Calculate  the  per  cent  of  phosphoric  acid, 
as  in  analysis  of  hydro-disodium-phosphate. 

It  is  well  after  dissolving  the  precipitate  of  phospho- 
molybdate  in  ammonia,  to  let  the  solution  stand  for  some 
hours,  to  allow  the  silica  to  separate  from  any  silico-molyb- 
date  that  may  possibly  be  present,  before  adding  the 
magnesium  mixture.  Should  any  silica  be  deposited,  by 
the  decomposition  of  silico-molybdate  in  the  ammoniacal 
solution,  filter  it  out,  add  the  magnesium  mixture,  and 
proceed  as  above. 

To  determine  the  water,  as  some  may  remain  after  dry- 
ing the  limestone  at  150°  C,  proceed  as  directed  in  the 
analysis  of  hydro-disodium  phosphate,  weighing  it  after 
absorption  in  calcium  chloride. 

To  determine  the  organic  matter  the  same  method  can 
be  followed  as  that  suggested  for  the  determination  of 
carbonic  acid,  in  anhydrous  carbonates,  by  fusion  with 
borax.  (See  Fres.,  §  139 — II. — c.)  The  loss  of  weight  will 
be  carbonic  acid,  water,  and  organic  matter.  The  differ- 
ence between  this  and  the  sum  of  the  weights  of  carbonic 
acid  and  water  previously  determined  will  be  the  weight 
of  organic  matter.  Of  course,  the  fusion  with  borax  must 
be  carefully  done,  and  the  determination  of  carbonic  acid 
and  water  be  accurate,  to  give  correct  results. 

Another  method  is,  to  dissolve  15  or  20  gms.  of  the 
limestone  in  dilute  hydrochloric  acid,  heat  it  gently  to 
expel  carbonic  acid,   filter  out  any  undissolved  residue 


64  LIMESTONE. 

through  ignited  asbestos,  wash  it  well  with  water,  dry  it, 
transfer  it,  with  the  asbestos,  to  a  platinum  boat,  intro- 
duce the  boat  into  a  combustion-tube  of  hard  glass 
containing  oxide  of  copper,  and  ignite  it  in  a  current  of 
dry  oxygen,  absorbing  the  resulting  carbonic  acid,  and 
from  it  calculating  the  carbon,  58  parts  of  which,  accord- 
ing to  Petzholdt,  correspond  to  100  parts  of  humus.  (See 
Jour./.  PraM.  Chem.,  LXIIL,  194.) 

To  determine  barium,  strontium,  and  manganese,  evapo- 
rate to  dryness  the  filtrate  from  the  residue  used  for  the 
determination  of  organic  matter,  and  heat  in  an  air-bath 
at  100°  C,  until  the  odor  of  hydrochloric  acid  disappears. 
Then  moisten  with  hydrochloric  acid,  digest  with  hot 
water,  filter,  and  wash.  The  residue  will  consist  of 
silica,  and  perhaps  baryta,  and  strontia  in  the  form  of 
sulphates  ;  while  the  filtrate  will  contain  the  manganese, 
with  other  constituents  of  the  limestone. 

Expel  the  silica  from  the  residue  with  ammonium 
fluoride  and  sulphuric  acid,  in  the  manner  described  in 
the  analysis  of  feldspar.  If  any  residue  remain,  fuse 
it  with  sodium  carbonate,  digest  with  hot  water,  filter, 
and  wash  well.  Barium  and  strontium  will  remain  on  the 
filter  as  carbonates.  Dissolve  them  through  the  filter 
with  dilute  hydrochloric  acid,  nearly  neutralize  the  solu- 
tion with  ammonia,  and  add  a  few  drops  of  sulphuric 
acid,  and  allow  to  stand  for  some  hours.  Should  a  pre- 
cipitate of  barium  sulphate,  and  perhaps  strontium  sul- 
phate form,  filter  it  out  and  wash  it,  and  allow  the  filtrate 
and  washings  to  run  into  a  small  flask.  Then  stop  the 
point  of  the  funnel,  fill  the  filter  with  a  strong  solution  of 
ammonium  carbonate,  and  allow  it  to  stand  for  12  hours. 
By  this  means,  the  strontium  sulphate  will  be  converted 
into  carbonate,  while  the  barium  sulphate  will  be 
unattacked.  Remove  the  plug  from  the  point  of  the 
funnel,  allow  the  fluid  to  run  into  the  flask  with  the  first 
filtrate,  wash  with  hot  water,  and  run  dilute  hydrochloric 
acid  through  the  filter  into  the  flask  ;  the  object  of  using 


STRONTIA — MANGANESE— CHLORINE.  65 

which  is  to  prevent  loss  by  effervescence  by  the  contact  of 
the  acid  with  the  solution  of  alkaline  carbonate  below. 
Finally,  wash  with,  water,  dry  the  filter  and  contents,  and 
determine  the  barium  sulphate  as  usual. 

To  the  combined  filtrates  in  the  flask  add  ammonia  and 
ammonium  carbonate,  and  if  a  precipitate  of  strontium 
carbonate  forms,  filter  it  through  a  very  small  filter,  wash 
with  dilute  ammonia,  dry,  ignite,  and  weigh  the 
strontium  carbonate.  Be  careful  to  clean  the  filter  well, 
and  ignite  it  separately .     (See  Fres. ,  §§  72  and  102. ) 

To  the  first  filtrate  from  the  silica,  baryta,  and  strontia 
add  a  few  drops  of  nitric  acid,  boil,  dilute,  nearly  neu- 
tralize with  sodium  carbonate,  add  excess  of  sodium 
acetate,  boil  and  filter  out  the  ferric  hydrate,  alumina  and 
phosphoric  acid,  wash  slightly,  concentrate  to  small  bulk, 
filter  again  if  necessary,  run  the  solution,  rendered 
alkaline  by  a  few  drops  of  ammonia,  into  a  small  flask, 
nearly  fill  the  flask,  add  freshly-prepared  ammonium 
sulphide,  cork  the  flask,  and  set  it  aside  for  24  hours  for 
the  manganese  sulphide  to  precipitate.  When  the  man- 
ganese sulphide  has  entirely  settled,  decant  off  the  clear 
fluid  into  a  beaker,  not  on  a  filter,  wash  by  decantation  into 
a  beaker  3  or  4  times,  with  water  containing  ammonium 
sulphide  and  a  little  ammonium  chloride,  and  then  on  a 
filter  with  the  same.  Then  transfer  the  moist  precipitate 
to  a  small  beaker,  add  hydrochloric  acid,  warm  until  the 
mixture  smells  no  longer  of  hydrogen  sulphide,  dilute 
slightly,  filter,  and  wash  carefully.  Then  heat  the  fluid 
to  boiling,  remove  the  heat,  add  solution  of  sodium  car- 
bonate until  the  fluid  is  distinctly  alkaline,  boil  until  the 
carbonic  acid  is  expelled,  filter,  wash  with  hot  water  until 
the  washings  are  not  alkaline  to  test-paper,  dry,  ignite, 
cool,  and  weigh  the  manganous-manganic  oxide  (Mn304), 
and  calculate  the  manganous  oxide  (MnO). 

To  determine  the  chlorine,  dissolve  40  or  50  gms.  of  the 
limestone  in  nitric  acid,  filter,  if  necessary,  and  determine 
the  chlorine  as  directed  in  the  analysis  of  barium  chloride. 


66  LIMESTONE. 

To  determine  the  fluorine,  dissolve  40  or  50  gms.  of  the 
limestone  in  acetic  acid,  filter,  and  in  the  residue  determine 
the  fluorine,  by  fusing  and  proceeding  as  directed  in  the 
analysis  of  calcium  fluoride. 

To  determine  the  alkalies,  dissolve  about  20  gms.  of  the 
mineral  in  hydrochloric  acid,  add  chlorine  water  and  heat 
for  a  short  time.  Should  there  be  any  residue,  filter  it 
out  and  decompose  it  by  J.  Lawrence  Smith's  method> 
given  in  analysis  of  feldspar.  Combine  the  filtrate,, 
which  may  contain  some  alkali,  with  the  main  solution. 
Then  add  ammonia  in  slight  excess,  and  ammonium  car- 
bonate, and  allow  the  solution  to  stand  for  several  hours  ; 
after  this,  filter,  wash,  evaporate  the  filtrate  and  washings 
to  dryness,  in  a  platinum  dish,  and  expel  the  ammonia 
salts  by  igniting  to  a  point  just  below  redness.  Dissolve 
in  water,  add  solution  of  barium  hydrate,  until  the  fluid 
is  decidedly  alkaline,  filter  and  wash  well,  and  add  to  the 
filtrate  solution  of  ammonium  carbonate  as  long  as  it  pro- 
duces a  precipitate,  allow  the  fluid  to  stand  for  a  short 
time,  filter  out  the  barium  carbonate,  and  wash  it  until 
the  washings  do  not  render  silver  nitrate  turbid.  Then 
evaporate  the  filtrate  in  a  weighed  platinum  dish,  after 
adding  a  drop  of  hydrochloric  acid,  ignite  to  faint  redness, 
cool,  and  weigh  the  mixed  chlorides  of  the  alkalies.  It  is 
well  to  dissolve  in  water,  and  repeat  the  treatment  with 
barium  hydrate  and  ammonium  carbonate,  and  again 
evaporate  and  weigh.  Separate  the  alkalies,  and  deter- 
mine them  as  directed  in  analysis  of  feldspar. 


CHAPTER    XII. 

CLAY. 

Clay  is  derived  principally  from  the  decomposition 
of  feldspar,  or  rather  feldspathic  rocks,  and  varies  in 
composition  and  color,  on  account  of  varying  quantities 
of  feldspar  sand  (or  feldspar  reduced  to  a  granular  condi- 
tion and  not  decomposed),  quartz  in  the  form  of  sand, 
lime,  magnesia,  oxide  of  iron,  and  manganese.  Some- 
times oxide  of  titanium  and  other  minerals  in  small 
quantities  are  found. 

The  kinds  of  clay  more  commonly  known  are  common 
brick  clay,  ordinary  pottery  clay,  slate,  fire-clay,  and 
kaolin  or  porcelain  clay.  The  difference  between  them  is 
due  less  to  the  character  of  the  constituents  than  to  their 
relative  quantity. 

It  is  sometimes  necessary  to  make  a  mechanical 
analysis  by  separation  of  the  coarse  from  the  fine  parts. 
For  description  of  methods,  and  of  apparatus,  consult 
Jour.  f.  Prakt.  Chem.,  XLVIL,  241,  and  Am.  Jour.  ScL 
&  Arts,  3d  series,  VI.,  288. 

For  the  chemical  analysis  dry  20  or  30  gms.  of  the 
finely-pulverized  clay  at  a  temperature  of  100°  C.  to  con- 
stant weight,  and  keep  the  powder  in  a  well-corked  bottle. 

The  loss  of  weight  in  drying  will  be  equivalent  to  the 
water. 

Fuse  1  gm.  of  the  dry  powder  with  a  mixture  of  equal 
parts  by  weight  of  sodium  and  potassium  carbonates,  and 
proceed  exactly  as  directed  in  the  analysis  of  feldspar, 
for  the  determination  of  silica,  oxide  of  iron,  aluminar 
lime,  and  magnesia. 

After  weighing  the  silica,  expel  it  by  Rose' s  method, 
with  ammonium  fluoride,  and  test  any  residue  which 
remains     qualitatively    for    titanium.       Should   any    be 


68  CLAY. 

detected,  fuse  5  gms.  of  the  feldspar  with  sodium 
fluoride  and  acid  sodium  sulphate,  as  directed  in  partial 
analysis  of  iron  ore,  bring  into  cold  water  solution,  add 
excess  of  potassium  hydrate,  filter  out  the  precipitated 
titanium  dioxide,  wash,  dry,  transfer  the  precipitate  to  a 
capacious  platinum  crucible,  burn  the  filter  and  add  the 
ash,  and  fuse  all  with  10  or  12  times  the  weight  of  acid 
sodium  sulphate.  Cool  and  digest  with  concentrated  sul- 
phuric acid.  When  the  mass  is  cool,  dissolve  it  in  cold 
water,  and  precipitate  the  titanium  dioxide  by  boiling. 
(Compare  analysis  of  titaniferous  iron  ore,  Note  7.) 

For  the  determination  of  manganese  and  other  con- 
stituents, consult  analysis  of  limestone. 

Determine  the  alkalies  as  in  analysis  of  feldspar. 

To  ascertain  how  much  of  the  silica  found  exists  in  com- 
bination with  the  bases  of  the  clay,  how  much  as  hydrated 
acid,  and  how  much  as  quartz  sand,  or  as  a  silicate 
present  in  the  form  of  sand,  proceed  as  follows.  (Compare 
Fres.  Quant.  Anal.,  5th  ed.  1865,  §236.) 

Let  A  represent  silica  in  combination  with  bases  of  the 
clay. 

Let  B  represent  hydrated  silicic  acid. 

Let  C  represent  quartz  sand,  and  silicates  in  the  form  of 
sand,  e.  g.,  feldspar  sand. 

Dry  2  gms.  of  the  clay  at  a  temperature  of  100°  C,  heat 
with  sulphuric  acid,  to  which  a  little  water  has  been 
added,  for  8  or  10  hours,  evaporate  to  dryness,  cool,  add 
water,  filter  out  the  undissolved  residue,  wash,  dry,  and 
weigh  ( A-\-B-\-C).  Then  treat  it  with  sodium  carbonate  as 
directed  by  Rose,  p.  923.  Transfer  it,  in  small  portions  at 
a  time,  to  a  boiling  solution  of  sodium  carbonate  contained 
in  a  platinum  dish,  boil  for  some  time,  and  filter  off  each 
time,  still  very  hot.  When  all  is  transferred  to  the  dish, 
boil  repeatedly  with  strong  solution  of  sodium  carbonate, 
until  a  few  drops  of  the  fluid,  finally  passing  through  the 
filter,  remain  clear  on  warming  with  ammonium  chloride. 
Wash  the  residue,  first  with  hot  water,  then  (to  insure  the 


SILICA,    FREE  AND   COMBINED.  69 

removal  of  every  trace  of  sodium  carbonate  which  may 
still  adhere  to  it)  with  water  slightly  acidified  with  hydro- 
chloric acid,  and  finally  with  water.  This  will  dissolve 
(A+B),  and  leave  a  residue  (C)  of  sand,  which  dry,  ignite, 
and  weigh. 

To  determine  (B)  boil  4  or  5  gms.  of  the  clay  (previously 
dried  at  100°  C.)  directly  with  a  strong  solution  of  sodium 
carbonate,  in  a  platinum  dish  as  above,  filter  and  wash 
thoroughly  with  hot  water.  Acidify  the  filtrate  with 
hydrochloric  acid,  evaporate  to  dryness,  and  determine 
the  silica  as  usual.  It  represents  (B)  or  the  hydrated 
silicic  acid. 

Add  together  the  weights  of  (B)  and  ,(0),  thus  found, 
and  subtract  the  sum  from  the  weight  of  the  first  residue 
{A+B+O).  The  difference  will  be  the  weight  of  (A)  or 
the  silica  in  combination  with  bases  of  the  clay. 

If  the  weight  of  (A-\~B-\-C)  found  here  be  the  same  as 
that  of  the  silica  found  by  fusion  in  a  similar  quantity,  in 
the  analysis  of  the  clay,  the  sand  is  quartz,  but  if  the 
weight  of  (A-\-B-{-C)  be  greater,  then  the  sand  contains 
silicates. 

The  weight  of  the  bases  combined  with  silica  to  silicates 
can  be  found  by  subtracting  the  weight  of  total  silica 
found  in  1  gm.  in  the  regular  analysis,  from  the  weight  ol 
(A+B+C)  in  1  gm. 


CHAPTEE    XIII. 

MANGANESE   ORE. 

If  it  is  required  to  determine  the  amount  of  metallic 
manganese  that  an  ore  will  yield,  dissolve  1  gm.  of  the 
ore  (finely  pulverized,  and  previously  dried  by  exposure 
in  an  air-bath,  to*  a  temperature  of  100°  C.  for  6  hours),  in 
a  mixture  of  about  10  c.  c.  of  concentrated  hydrochloric 
acid,  2  c.  c.  of  strong  nitric  acid,  and  10  c.  c.  of  water,  in 
a  small  flask.  When  the  ore  is  decomposed,  filter  out  the 
insoluble  residue,  which  should  be  light  colored,  and  wash 
well.  Pour  filtrate  and  washings  into  a  flask,  of  a  capacity 
of  at  least  1  litre,  add  a  saturated  solution  of  crystallized 
sodium  carbonate,  little  by  little,  until  tho  fluid  becomes 
dark  red  in  color,  but  remains  clear,  thus  showing  that 
not  quite  all  the  free  hydrochloric  acid  is  neutralized. 
Then  add  a  solution  of  about  5  gms.  of  sodium  acetate, 
dilute  to  500  c.  c. ,  heat  to  boiling,  and  continue  boiling  for 
o  minutes.  Then  remove  the  heat,  allow  the  precipitate 
of  basic  acetates  of  iron  and  alumina  to  settle,  filter  hot, 
and  wash  slightly. 

The  water  required  to  remove  the  precipitate  from  the 
flask  to  the  filter  will  be  sufficient  to  wash  ifc.  Begin  at 
once  to  evaporate  the  first  filtrate,  and  while  doing  so,  dis- 
solve the  precipitate  in  as  little  hot  hydrochloric  acid  as 
possible,  pour  the  solution  back  into  the  flask,  repeat  the 
precipitation  in  the  same  way,  filter,  and  wash  moderately. 
Add  this  filtrate  to  the  first  one,  and  concentrate  both  to 
700  c.  c.  if  possible.  It  is  better  to  use  a  capacious  porce- 
lain dish  for  the  purpose.  To  this  concentrated  solution, 
add  sodium  carbonate,  until  a  slight  permanent  precipitate 
is  formed,  and  then  acetic  acid  until  it  is  dissolved.  Heat 
to  boiling,  remove  the  heat,  add  bromine  water  until  the 


MANGANESE.  71 

solution  has  a  decided  color,  and  continue  to  heat  to  a 
point  just  below  boiling,  until  the  fluid  becomes  colorless. 
Remove  the  heat,  allow  the  precipitate  to  settle,  add  a 
little  more  bromine  water  carefully,  so  as  not  to  disturb 
the  precipitate,  and  heat  again,  as  before,  until  tho  fluid 
loses  the  bromine  color.  Continue  this  treatment  until 
the  bromine  no  longer  produces  a  precipitate.  Filter  out 
the  precipitate  of  manganese  oxide,  wash  slightly,  and,  to 
be  sure  that  the  filtrate  contains  no  manganese,  neutralize 
it  again  with  sodium  carbonate,  acidify  ic  with  acetic  acid, 
and  proceed  as  before.  When  the  manganese  oxide  is  all 
precipitated,  transfer,  with  a  spatula,  as  much  of  the 
precipitate  as  possible  from  the  filters  to  a  small 
beaker,  dissolve  what  oxide  may  remain  on  the  filters  by 
pouring  hot  dilute  hydrochloric  acid  through  them  into 
the  beaker,  and  heat  to  effect  solution.  Heat  the 
solution  to  incipient  boiling,  remove  the  heat,  add  solution 
of  sodium  carbonate  until  the  fluid  is  alkaline,  and  boil 
until  carbonic  acid  is  expelled.  Usually,  boiling  for  5  or 
10  minutes  will  effect  this.  Then,  filter  ou '  the  manganese 
carbonate,  and  wash  with  hot  water  until  the  washings  do 
not  turn  reddened  litmus-paper  blue.  To  test  this,  hold  a 
narrow  strip  of  the  paper  against  the  point  of  the  funnel, 
so  as  to  bring  it  in  contact  with  the  washings,  as  they  run 
through.  Finally,  dry  the  precipitate,  ignite  it  in  a 
weighed  crucible,  cool,  and  weigh  the  manganoso-man- 
ganic  oxide  (Mn304),  and  calculate  the  manganese.  After 
weighing,  it  is  well  to  ignite  the  precipitate,  and  weigh 
again.  If  the  precipitate  is  very  small,  it  may  be  ignited 
rolled  up  in  the  filter. 

If  the  ore  contains  very  little  iron  oxide,  the  method  of 
neutralizing  the  acid  solution  with  sodium  carbonate  until 
it  becomes  dark  red,  cannot  be  followed,  as  there  may  not 
be  sufficient  iron  to  give  the  color.  In  such  a  case,  add 
solution  of  sodium  carbonate  until  a  very  slight  permanent 
precipitate  is  formed,  and  then  hydrochloric  acid,  drop  by 
drop,  until  the  solution  is  slightly  acid,  and,  finally,  a  solu- 


72  MANGANESE   0KE. 

tion  of  about  5  gms.  of  sodium  acetate,  and  then  proceed 
as  directed  above. 

If  the  ore  contains  silicate  of  manganese,  fu3e  with 
sodium  carbonate,  and  then  dissolve  in  acid,  and  proceed 
as  above. 

In  all  cases  where  the  acid  fails  to  decompose  the  ore, 
leaving  a  dark  residue,  it"  is  better  to  decompose  the 
residue  by  fusion,  dissolve  the  fused  mass  in  acid,  and  add 
the  solution  to  the  principal  one. 

If  the  ore  is  completely  decomposed  by  acid  in  the  first 
instance,  only  a  white,  pulverulent,  siliceous  residue 
should  be  left. 

The  commercial  value  of  manganese  ore  depends  chiefly 
upon  the  quantity  of  chlorine  it  will  yield  when  treated 
with  hydrochloric  acid. 

By  available  oxygen  is  meant  the  excess  of  oxygen  over 
the  1  atom  combined  with  manganese  to  form  monoxide, 
and,  as  only  half  of  the  oxygen  of  manganese  dioxide  is 
available,  16  parts  of  oxygen  are  equivalent  to  87  parts  of 
manganese  dioxide,  and,  as  in  the  decomposition  of  1 
molecule  of  manganese  dioxide  by  hydrochloric  acid  2 
atoms  of  chlorine  are  liberated,  16  parts  of  oxygen  are 
also  equivalent  to  71  parts  of  chlorine. 

To  determine  the  available  oxygen,  introduce  into  flask 
"  B  "  of  the  apparatus  described  in  the  analysis  of  calcite, 
about  3  gms.  of  the  ore,  very  finely  pulverized,  and  care- 
fully dried  at  100°  C.  The  best  method  of  determining 
the  quantity  of  ore  taken  is  that  described  in  the  analysis 
of  potash  alum,  by  weighing  a  tube  containing  pulverized 
and  dried  ore,  shaking  out  the  desired  quantity,  again 
weighing  the  tube  and  determining  the  weight  of  ore 
taken  by  the  loss.  Introduce  also  into  the  flask  about  7 
or  8  gms.  of  neutral  potassium  oxalate,  and  as  much  water 
as  will  fill  it  to  about  one  quarter.  Fill  flasks  "A"  and 
"  C  "  of  the  apparatus  about  one  quarter  full  of  pure  con- 
centrated sulphuric  acid.  Put  the  apparatus  together, 
weigh  it,  and  proceed  as  directed  in  the  analysis  of  cal- 


AVAIL-ABLE   OXYGEN.  73 

cium  carbonate,  for  the  determination  of  carbonic  acid  by 
loss,  drawing  about  1  litre  of  air  through  the  flasks,  very 
slowly,  by  means  of  an  aspirator,  not  allowing  air-bubbles 
to  pass  faster  than  2  per  second.  The  heat  generated  by 
the  union  of  the  water  and  sulphuric  acid  is  sufficient. 
The  difference  in  the  weight  of  the  apparatus,  before  and 
after  the  operation,  is  equivalent  to  the  weight  of  carbonic 
acid  lost.     (Fres.,  §230.) 

The  method  of  calculating  the  available  oxygen  is  evi- 
dent upon  an  examination  of  the  equation  representing 
the  reaction : 
Mn09+KsC804+2HBS04=MnS04+K,S04+2H80+2C09. 

Two  molecules  of  carbonic  acid  are  equivalent  to  one 
molecule  of  manganese  dioxide,  i.  e.,  88  parts  by  weight 
of  carbonic  acid  represent  87  parts  by  weight  of  man- 
ganese dioxide.  Therefore,  if  the  weight  of  carbonic  acid 
is  multiplied  by  87,  and  the  product  divided  by  88,  the 
quotient  will  be  the  weight  of  manganese  dioxide.  As 
only  one  half  of  the  oxygen  of  manganese  dioxide  is' 
available,  it  is  calculated  by  a  simple  proportion,  viz., 
87 :  16= weight  of  Mn02 ;  weight  of  available  0. 

Some  ores  of  manganese  contain  carbonates,  the  carbonic 
acid  of  which  must,  of  course,  be  removed  before  the 
analysis  is  made.  If  such  be  the  case,  introduce  the  ore 
as  before  into  flask  "B,"  fill  it  about  one  quarter  full 
with  water,  add  dilute  sulphuric  acid  (1  part  acid  to  5 
parts  water),  little  by  little,  until  effervescence  ceases,  and 
the  fluid  remains  acid  after  boiling  out  the  carbonic  acid. 
Then  neutralize  the  excess  of  acid  with  sodium  or  potas- 
sium hydrate,  free  from  carbonic  acid,  add  the  usual 
quantity  of  neutral  oxalate,  and  proceed  as  before.  (Zeit- 
scJirift  f.  Analyt.   Chem.,  1,  48.) 

Another  method  is  that  known  as  the  iron  method. 
Fresenius's  directions  (p.  512)  are  to  dissolve  in  a  long- 
necked  flask,  placed  in  a  slanting  position,  1  gm.  of  piano- 
forte wire,  and  dissolve  it  in  pure  concentrated  hydro- 
chloric acid;  then  weigh  about  0. 600  gm.  of  the  ore,  in  a  little 


« 


9 


74  MANGANESE   ORE. 

tube,  drop  this  with  its  contents  into  the  flask,  and  heat 
cautiously  until  the  ore  is  dissolved.  One  eq.  of  man- 
ganese dioxide,  or  87  parts,  converts  2  eqs.  of  iron,  or  112 
parts,  from  the  state  of  ferrous  to  that  of  ferric  chloride. 
When  complete  solution  has  taken  place,  dilute  the  con- 
tents of  the  flask  with  water,  allow  to  cool,  rinse  into  a 
beaker,  and  determine  the  iron  still  remaining  in  the  state 
of  ferrous  chloride  with  potassium  bichromate.  (See 
analysis  of  ammonio  ferric  sulphate.)  Deduct  this  from 
the  weight  of  the  wire  employed  in  the  process.  The  dif- 
ference expresses  the  quantity  of  iron,  which  has  been 
converted  by  the  oxygen  of  the  manganese  from  ferrous 
to  ferric  chloride.  This  difference,  multiplied  by  87,  and 
divided  by  112,  gives  the  amount  of  manganese  dioxide  in 
the  ore. 

Pattinson  has  suggested  a  modification  of  this  method, 
fin  a  paper  read  before  the  Newcastle-upon-Tyne  Chem. 
Soc,  Jan.  27,  1870.  His  test  analyses  are  very  satisfac- 
tory. He  directs  to  dissolve  about  2  gms.  of  clean  iron 
wire  in  a  flask  holding  about  500  c.  c,  with  about  90  c.  c. 
of  dilute  sulphuric  acid,  made  by  adding  3  parts  of  water 
to  1  part  of  the  acid.  A  cork,  through  which  passes  a 
tube  bent  twice  at  right  angles,  is  inserted  in  the  neck  of 
the  flask,  and  the  flask  is  heated  over  a  gas  flame  until  the 
iron  is  dissolved.  The  bent  tube  is  placed  so  as  to  dip 
into  a  small  flask  or  beaker  containing  a  little  water. 
When  the  iron  is  quite  dissolved,  2  gms.  of  the  finely 
pounded  and  dried  sample  of  manganese  ore  to  be  tested 
are  put  into  the  flask,  the  cork  replaced,  and  the  contents 
again  made  to  boil  gently  over  a  gas  flame,  until  it  is  seen 
that  the  whole  of  the  black  part  of  the  sample  is  dis- 
solved. The  water  in  the  small  flask  or  beaker  is  then 
allowed  to  recede  through  the  bent  tube  into  the  larger 
flask,  more  distilled  water  is  added  to  rinse  out  the  small 
flask  or  beaker  and  bent  tube,  the  cork  well  rinsed,  and 
the  contents  of  the  flask  made  up  to  about  250  or  300  c.  c. 
with  distilled  water.      The  amount  of  iron  remaining  un= 


HC1  EEQUIKED   FOR   DECOMPOSITION.  75 

oxidized  in  the  solution  is  then  ascertained  by  means  of  a 
standard  solution  of  potassium  bichromate.  The  amount 
the  bichromate  indicates,  deducted  from  the  total  amount 
of  iron  used,  gives  the  amount  of  iron  which  has  been 
oxidized  to  the  ferric  form  by  the  manganese  ore,  and 
from  which  can  be  calculated  the  percentage  of  peroxide 
of  manganese  contained  in  the  ore.  Thus,  supposing  that 
0.250  gm.  of  iron  remained  unoxidized,  then  if  2  gms.  of 
iron  were  taken  at  first,  1.750  gms.  of  iron  will  have 
been  oxidized  by  the  ore.     Then  as 

112  :  87  =  1.750 : 1.359  gm.  Mn02, 
which,  if  2  gms.  of  ore  were  taken  for  the  test,  would  rep- 
resent 67.95  per  cent  of  Mn02  in  the  ore. 

Standardized  solution  of  potassium  permanganate  can 
be  used  instead  of  bichromate. 

It  is  frequently  of  importance  to  know  the  amount  of 
hydrochloric  acid  necessary  to  decompose  an  ore  of  man- 
ganese.    This  can  be  determined  with  sufficient  accurac 
for  commercial  purposes,  by  what  is  called  Kiefer's  solu- 
tion.   (Ann.  d.  Chem.  u.  Pharm.,  XCIII.,  386.) 

To  prepare  the  solution,  dissolve  15  gms.  recrystallized 
copper  sulphate  in  100  c.  c.  of  warm  water,  and  add  am- 
monia, with  stirring,  until  the  basic  salt  is  nearly  dissolved. 
Should  the  point  be  overstepped,  add  more  copper  sul- 
phate, and  repeat.  Filter  the  solution,  and  add  the  filtrate 
from  a  burette,  with  constant  stirring,  to  10  c.  c.  of  half- 
normal  sulphuric  acid,  until  a  permanent  turbidity  is  pro- 
duced, and  note  the  number  of  c.  c.  used.  As  10  c.  c.  of 
half -normal  sulphuric  acid  is  equivalent  to  0.365  gm.  of 
hydrochloric  acid,  this,  divided  by  the  number  of  c.  c.  of 
the  copper  sulphate  solution  used,  shows  the  quantity  of 
hydrochloric  acid  represented  by  1  c.  c.  of  it.  This  is 
standard  oopper  sulphate  solution. 

The  next  step  is  to  prepare  a  solution  of  hydrochloric 
acid  of  1.1  sp.  gr.,  and  to  10  c.  c.  of  it  add  the  standard 
copper  sulphate  solution,  drop  by  drop,  with  constant 
stirring,    until  the    fluid   becomes  slightly  turbid.      The 


c 

to 


76  MANGANESE   OEE. 

number  of  c.  c.  of  copper  sulphate  solution  used  multi« 
plied  by  the  previously  ascertained  value  of  1  c.  c.  of  it, 
gives  the  quantity  of  hydrochloric  acid  in  the  hydro- 
chloric acid  solution  of  1.1  sp.  gr. 

Then,  into  a  flask,  through  the  cork  of  which  passes  a 
tube  about  3  feet  long,  and  of  about  one  quarter  of  an 
inch  diameter,  and  bent  slightly  from  the  perpendicular, 
introduce  1  gm.  of  the  manganese  ore  to  be  tested  and  10 
c.  c.  of  the  standardized  hydrochloric  acid,  and  heat 
gently  until  the  ore  is  decomposed,  and  then  more  strongly 
for  a  few  minutes  until  the  chlorine  is  expelled. 

The  object  of  the  long  tube  is  to  condense  the  vapor, 
and  allow  the  fluid  to  run  back  into  the  flask.  To  insure 
this,  it  is  well  to  wrap  it  with  a  wet  cloth  and  keep  it  cool. 

After  the  chlorine  is  expelled,  cool  the  flask,  add  25 
c.  c.  of  cold  water,  filter,  and  wash  with  25  or  30  c.  c.  of 
cold  water.  Then  to  the  filtrate  add,  as  before,  standard 
opper  sulphate  solution,  until  the  fluid  is  slightly  turbid. 
The  number  of  c.  c.  used  shows  the  quantity  of  free 
hydrochloric  acid  present. 

The  difference  between  the  quantity  of  hydrochloric 
acid  found  in  10  c.  c.  of  the  solution  of  1.1  sp.  gr.  before 
adding  it  to  the  ore,  and  the  quantity  in  10  c.  c.  after 
using  it  for  dissolving  the  ore,  gives  the  quantity  required 
to  dissolve  1  gm.  of  the  ore. 

The  calculation  of  the  manganese  oxides  in  an  ore  is 
best  illustrated  by  an  example  : 

Suppose  total  Mn  =  25.24  per  cent  and  available  O  =  6  per  cent. 
Calculate  first  the  available  oxygen  to  make  Mn02 

(O)  16  :(Mn08)  87  =  6:34.62. 
Calculate  the  Mn  corresponding  to  this  : 

(Mn02)  87  :(Mn)  55  =  32.62  :  20.62. 

Total  Mn  as  above 25.24 

Mn  as  MnOs  calculated  above 20.62 

Difference 4.62  per  cent  Mn 

Calculate  this  as  MnO.    It  is  equivalent  to  5.96  per  cent,  since 
(Mn)  55  :(MnO)  71  =  4.62  : 5.96. 


CALCULATION   OF   OXIDES.  77 

Calculate  MnOa  required  to  combine  with  this  to  form  Mn208  : 
(MnO)  71  :(Mn02)  87  =  5.96  : 7.30.     MnO  +  Mn02  =  Mn203. 

Mn208,  then,  is  (MnO  =  5.96)  +  (Mn03  =  7.30)  =  13.26  per  cent  Mn,Ot. 
Total  MnO  3  calculated  from  available  O  =  32.62 
Deduct  MnO,  combining  to  form  Mn808  =     7.30 

Difference  =  Mn08  existing  as  such 25.32 

Or  the  ore  contains 

Mn2Oa 13.86  per  cent. 

MnO, 25.32  per  cent. 


CHAPTER    XIV. 

PARTIAL   ANALYSIS   OF  IKON   ORE* 
FOR    SILICA,    IRONj    SULPHUR,  AND  PHOSPHORUS. 

Pulverize  7  or  8  gms.  of  the  ore  to  impalpable  powder 
in  an  agate  mortar,  weigh  exactly  5  gms.  of  the  powder, 
and  mix  it  carefully,  in  a  large  clock-glass,  with  25  gms.  of 
dry  sodium  carbonate  and  2.5  gms.  of  sodium  nitrate, 
previously  pulverized.  Introduce  about  one  third  of  the 
mixture  into  a  capacious  platinum  crucible,  provided  with 
a  cover,  and  heat  over  a  strong  Bunsen  burner  until  the 
mass  ceases  to  swell  in  the  crucible  from  the  action  of  the 

ses.  Then  allow  the  crucible  to  cool  to  a  point  below 
edness,  introduce  about  the  same  quantity,  and  treat  it 

the  same  way.  Finally,  transfer  the  remainder  to  the 
crucible,  and,  after  heating  over  the  Bunsen  flame  until 
the  contents  of  the  crucible  become  quiet,  apply  the 
strongest  heat  of  a  good  blast-lamp  until  the  contents  are 
reduced  to  quiet  fusion,  or,  as  w^^ometimes  be  the  case, 
asemi-fu^d  mass  results,  upon  wich  heat  seems  to  have 
no  more  effect.  Follow  the  directions  given  in  the 
analysis  of  feldspar,  for  removing  the  mass  from  the  cru- 
cible, and  cleansing  the  latter  from  adhering  particles. 
When  that  portion  of  the  contents  of  the  crucible,  which 
is  insoluble  in  water,  has  entirely  settled,  pour  off  the 
clear  fluid  into  another  vessel,  add  to  the  residue  20  or  30 
c.  c.  pure  concentrated  hydrochloric  acid,  together  with 
the  washings  of  the  crucible,  and  cover,  and  evaporate  on 
a  water-bath  nearly  to  dryness.  Then  dilute  with  a  little 
water ;  and  should  all  be  now  in  solution  (except  some 
separated  silica),  transfer  all  to  the  alkaline  water  solu- 
tion, cautiously  (keeping  the  vessel  covered  to  prevent 
loss  by  effervescence),  make  the  fluid  acid  with  hydro- 
chloric acid,  if  not  already  so,  heat  to  boiling  to  expel  car- 


IKON — SULPHITE.  79 

Ibonic  acid,  transfer  to  a  casserole,  evaporate  on  a  water- 
bath,  and  heat  in  an  air-bath.  (Compare  analysis  of  feld- 
spar.) Should  there  be  any  undecomposed  ore  after  the 
treatment  with  acid,  as  directed  above,  it  may  be  digested 
once  more,  with  concentrated  hydrochloric  acid,  and  the  so- 
lution added  to  the  first.  But  if  any  ore  resists  this  treat- 
ment, filter  it  out,  add  the  filtrate  to  the  other  solutions, 
dry  the  residue,  burn  it  in  a  platinum  crucible,  fuse  as 
before,  proportioning  the  flux  to  the  quantity  of  residue, 
and,  after  bringing  all  into  solution,  proceed  as  before. 
Should  the  ore  resist  this  treatment,  which  is  an  extreme 
case,  dry  and  fuse  the  filtered  residue  in  the  way  directed 
by  Hart  in  OTiem.  Gaz.,  1855,  458:  "Fuse  8  parts  of 
borax  in  a  platinum  crucible,  add  to  the  mass  in  fusion  1 
part  of  finely  pulverized  ore,  stir  constantly,  and  keep 
the  crucible  half  an  hour  longer  at  a  bright-red  heat,  add 
dry  carbonate  of  soda  as  long  as  it  causes  effervescence, 
then  gradually,  and  with  frequent  stirring  with  a 
platinum  wire,  3  parts  of  a  mixture  of  equal  parts  of 
nitrate  of  potassa  and  carbonate  of  soda,  and  keep 
the  mass  a  few  minutes  longer  in  fusion.  Remove  the 
mass  from  the  crucible  with  water,  dissolve  in  hydro- 
chloric acid,  and  combine  with  the  other  solutions  ;  evapo- 
rate all  to  dryness  on  a  water-bath,  dry  in  an  air-bath,  and 
proceed  to  the  determination  of  the  silica  as  directed  in 
the  analysis  of  feldspar. 

Dilute  the  acid  filtrate  from  the  silica  to  500  c.  c,  and 
divide  it  into  3  portions,  the  first  containing  100  c.  c,  in 
which  the  iron  and  sulphur  are  to  be  determined,  and  the 
other  two  containing  200  c.  c.  each,  in  which  the  phospho- 
rus is  to  be  determined  in  duplicate. 

In  the  first  portion,  which  is  equivalent  to  1  gm.  of  the 
ore,  precipitate  the  ferric  hydrate,  with  an  excess  of  am- 
monia, filter,  wash  until  a  few  drops  of  the  wash-water, 
acidulated  with  hydrochloric  acid,  give  no  reaction  with 
barium  chloride  solution,  for  sulphuric  acid.  Dis- 
solve the  precipitate  in  hot,  dilute  sulphuric  acid,  divide 


80  IRON    ORE — PARTIAL, 

the  solution  into  2  equal  portions,  reduce  them  with, 
amalgamated  zinc  and  platinum  in  proper  bottles,  and  de- 
termine the  iron  volumetrically  with  potassium  perman- 
ganate, as  directed  in  the  analysis  of  ammonio-ferric  sul- 
phate. If  the  ore  contain  titanic  acid,  it  must  be  re- 
moved before  reducing  the  ferric  to  ferrous  oxide,  as  the 
titanium  dioxide  is  also  reduced  to  sesquioxide  by  the 
action  of  the  zinc  and  platinum,  and  reoxidized  by  potas- 
sium permanganate.  Consequently,  more  permanganate 
will  be  decomposed  than  is  required  to  raise  the  ferrous  to 
ferric  oxide. 

For  the  method  of  proceeding  in  such  a  case,  consult 
analysis  of  titaniferous  iron  ore  (Note  7). 

After  precipitating  the  ferric  hydrate  from  the  portion 
containing  100  c.  c,  determine  the  sulphur  in  the  nitrate 
as  directed  in  the  analysis  of  magnesium  sulphate. 

The  phosphorus  is  to  be  determined  in  each  of  the  2 
portions  of  200  c.  c.  by  either  of  the  following  methods : 

First  Method. — The  ferric  oxide,  carrying  the  phosphoric 
acid,  is  precipitated  from  the  solution  by  ammonia,  fil- 
tered out,  and  washed  moderately  (the  water  required  to 
remove  the  precipitate  to  the  filter  being  sufficient).  The 
walls  of  the  glass,  in  which  the  precipitation  is  effected, 
are  washed  down  by  about  25  c.  c.  of  hot  concentrated 
nitric  acid.  To  this  the  precipitate  is  transferred  by 
means  of  a  spatula,  with  occasional  stirring.  After  re- 
moving from  the  filter  all  of  the  precipitate  that  can  be 
conveniently  reached  by  the  spatula,  the  solution  is 
heated,  and  poured  through  the  filter,  and  the  filter  well 
washed  with  water  into  a  beaker  of  medium  size.  By 
this  means  complete  solution  is  effected  in  a  very  short 
time.  This  solution  is  now  boiled  down  to  very  small 
bulk,  to  remove  all  chlorine  and  excess  of  nitric  acid,  di- 
luted to  a  volume  of  about  100  c.  c,  and  neutralized  by 
ammonia  to  a  light  mahogany  color.  To  this  a  sufficient 
quantity  of  solution  of  "ammonium  molybdate "  is 
added,  and  the  whole  kept  at  a  temperature  just  below 


PHOSPHORUS.  81 

boiling  for  2  or  3  hours,  and  then  allowed  to  stand  in  a 
warn,  place  for  12  hours  longer.  In  most  cases,  25  c.  c.  of  a 
solution  so  prepared  that  1  c.  c.  is  equivalent  to  0.001  gm. 
of  phosphoric  acid  will  be  sufficient.  When  the  precipi- 
tate has  settled,  it  is  filtered  out  and  washed  with  am- 
monium molybdate  solution  which  has  been  diluted  with 
an  equal  volume  of  water.  The  filtrate  is  again  partially 
neutralized  with  ammonia,  warmed,  and  allowed  to  stand 
in  a  warm  place  for  5  or  6  hours.  If  any  precipitate  occur, 
it  is  filtered  out,  and  treated  as  before,  and  the  filtrate 
tested  again.  In  rare  cases,  a  third  small  precipitate 
forms. 

The  washed  precipitates  of  phospho-molybdate  are  dis- 
solved through  the  filters  with  dilute  ammonia  into  the 
same  beaker,  and  the  filters  washed  with  water.  As  a 
small  amount  of  ferric  oxide,  enough  to  color  the  filter 
around  the  edge,  if  not  more,  almost  invariably  remains 
after  washing,  nitric  acid  is  now  poured  on  the  filter,  drop 
by  drop,  allowed  to  run  into  the  beaker  containing  the 
ammoniacal  solution,  the  filter  washed  with  a  little  water, 
4  or  5  c.  c.  of  ammonium  molybdate  solution  added,  to 
separate  any  phosphoric  acid  that  may  be  held  by  the 
ferric  oxide,  and  enough  more  nitric  acid  to  render  the 
solution  decidedly  acid,  avoiding  however  a  large  excess. 
By  this  means,  the  phospho-molybdate  is  precipitated  free 
from  iron,  which  may  have  been  carried  down  with  it  pre- 
viously. The  acid  solution  is  allowed  to  stand  for  a  few 
hours  in  a  warm  place,  until  the  supernatant  fluid  is  clear. 
It  is  well,  although  rarely  necessary,  to  test  this  fluid 
(after  filtering),  for  another  precipitate,  by  gently  warm- 
ing it,  and  allowing  it  to  stand  for  a  time.  The  re-precip- 
itated phospho-molybdate  is  filtered  out,  washed  with 
dilute  ammonium-molybdate  solution,  and  dissolved  with 
ammonia.  To  the  solution  is  added  enough  hydrochloric 
acid  to  make  it  acid,  about  0.050  gm.  of  tartaric  acid, 
then  enough  ammonia  to  render  it  decidedly  alkaline,  and 
finally  5  c.  c.  of  "magnesia  mixture."     The  object  aimed 


82  IKON    ORE — PARTIAL. 

at  in  adding  the  hydrochloric  acid  and  ammonia  is  the 
introduction  of  a  sufficient  amount  of  ammonium  chloride, 
to  prevent  the  precipitation  of  any  magnesium  salts  from 
the  magnesia  mixture  ;  while  the  tartaric  acid  is  intro- 
duced to  hold  up  any  trace  of  iron  that  maybe  in  the  solu- 
tion. 

After  adding  the  magnesia  mixture,  the  whole  is  set 
aside  in  the  cold,  until  the  precipitate  of  ammonio- 
magnesium-phosphate  is  entirely  formed,  when  it  is 
filtered,  washed  with  dilute  ammonia,  dried,  ignited,  and 
weighed.  Consult  analysis  of  hydro-disodium-phosphate. 
(Also  see  article  by  F.  A.  Cairns,  in  Am.  Chem.,  Dec, 
1876.) 

Second  Method. — Heat  the  hydrochloric  acid  solution  to 
boiling,  remove  the  heat,  and  add  a  saturated  solution  of 
pure  sodium  sulphite  (little  by  little),  and  more  hydro- 
chloric acid,  if  necessary,  until  the  fluid  becomes  colorless, 
showing  that  the  ferric  is  reduced  to  ferrous  chloride. 
Then  add  a  little  more  hydrochloric  acid,  and  boil  until 
the  odor  of  sulphurous  acid  disappears,  keeping  up  the 
volume  of  fluid  by  occasional  addition  of  hot  water. 
When  the  odor  of  sulphurous  acid  can  no  longer  be 
detected,  if  the  solution  should  not  have  acquired  a  yellow 
tint,  add  enough  potassium  permanganate  solution  to 
oxidize  about  0.150  gm.  of  the  ferrous  to  ferric  chloride, 
then  saturated  solution  of  sodium  carbonate,  until  a  per- 
manent precipitate  is  formed,  and  the  solution  slightly 
alkaline.  Then  make  the  solution  acid  with  acetic  acid, 
dilute  to  about  200  c.  c,  heat  to  boiling,  and  continue  to 
boil  for  8  or  10  minutes  ;  after  which  remove  the  heat  and 
allow  the  basic  acetate  of  iron  to  settle  completely.  It 
will  carry  all  but  perhaps  a  slight  trace  of  phosphoric  acid 
with  it.  Filter,  and  proceed  to  boil  the  filtrate  for  a 
second  small  precipitate,  to  insure  the  recovery  of  all  the 
phosphoric  acid. 

Dissolve  the  first  precipitate  by  pouring  hot  hydro- 
chloric acid  through  the  filter.     Should  it  fail  to  dissolve 


PHOSPHORUS.  83 

all  tlie  precipitate,  throw  the  filter  into  the  acid,  and 
digest  over  heat  nntil  the  solution  is  complete.  To  the 
clear  solution,  after  filtering,  if  necessary,  add  ammonia  in 
excess  (without  heating),  filter  out  the  ferric  hydrate,  and 
dissolve  it  by  pouring  hot  nitric  acid  through  the  filter. 
The  reason  for  dissolving  in  hydrochloric  acid  first,  is  that 
the  basic  acetate  is  apt  to  contain  a  quantity  of  a  modifi- 
cation of  ferric  oxide,  very  insoluble  in  nitric  acid,  but 
which  yields  readily  to  hydrochloric,  while  the  ferric 
oxide  re-precipitated  from  hydrochloric  acid  solution  by 
an  excess  of  ammonia  is  readily  soluble  in  hot  nitric 
acid. 

Boil  down  the  nitric  acid  solution  nearly  to  dryness,  in 
order  to  expel  all  chlorine,  dilute  with  hot  water  to  about 
100  c.  c,  nearly  neutralize  with  ammonia,  add  25  c.  c. 
ammonium  molybdate  solution,  heat  to  a  point  just  below 
boiling  for  2  or  3  hours,  and  allow  to  stand  in  a  warm 
place  for  12  hours  more.  After  the  precipitate  has  com- 
pletely subsided,  filter  and  wash  with  solution  of  am- 
monium molybdate,  diluted  with  an  equal  volume  of 
water.  Eeserve  the  filtrate,  which  may  contain  a  little 
phosphoric  acid,  to  be  used  to  dilute  the  nitric  acid  solu- 
tion of  the  second  precipitate  of  basic  acetate. 

Dissolve  the  precipitate  of  phospho-molybdate  of  am- 
monium through  the  filter  with  dilute  ammonia,  wash  the 
filter  with  20  or  30  c.  c.  of  water,  run  through  the  filter, 
into  the  ammoniacal  solution,  enough  dilute  nitric  acid  to 
dissolve  any  adhering  oxide  of  iron,  and  render  the  solu- 
tion slightly  acid,  adding  at  the  same  time  4  or  5  c.  c.  of 
ammonium  molybdate  solution,  and  allow  all  to  stand 
until  the  precipitate  brought  out  by  the  nitric  acid  has 
entirely  settled. 

This  re-precipitation  by  means  of  nitric  acid  is  made  to 
separate  any  traces  of  ferric  oxide,  which  will  remain  in 
solution  in  the  nitric  acid,  while  the  phospho-molybdate 
precipitates,  and  can,  by  filtering  and  washing  with  dilute 
ammonium    molybdate    solution,    be    (usually)    entirely 


I 


84  IRON   ORE — PARTIAL. 

freed  from  iron.  Set  this  precipitate,  which  contains 
nearly  all  the  phosphoric  acid,  on  one  side,  after  filtering 
and  washing  it  with  dilute  ammonium  molybdate  until  the 
treatment  of  the  second  precipitate  of  basic  acetate  is  com- 
pleted. 

Bring  this  second  precipitate  of  acetate  into  nitric  acid 
solution,  in  the  same  way  as  the  first  one,  boil  it  down 
nearly  to  dryness,  dilute  with  30  or  40  c.  c.  of  water, 
nearly  neutralize  with  ammonia,  and  add  to  it  the  filtrate 
from  the  first  precipitate  of  phospho-molybdate,  reserved 
for  the  purpose,  together  with  the  filtrate  from  the  re-pre- 
cipitation of  the  same  by  nitric  acid.  By  this  means,  all 
phosphoric  acid  which  may  not  have  been  precipitated 
will  be  in  the  solution.  Should  another  precipitate  appear 
in  this  solution,  after  heating  it,  and  allowing  it  to  stand 
as  before,  treat  it  in  the  same  manner  as  the  first  one. 
Dissolve  both  precipitates  through  the  filters,  which 
should  be  of  the  smallest  size,  into  the  same  beaker,  with 
as  little  dilute  ammonia  as  possible,  and  wash  them  with 
15  or  20  c.  c.  of  water. 

Finally  acidulate  with  hydrochloric  acid,  add  about 
0.050  gm.  of  tartaric  acid,  make  alkaline  with  ammonia, 
add  5  c.  c.  magnesia  mixture,  and  allow  to  stand  for  12 
hours,  and  proceed  as  in  analysis  of  hydro-disodium  phos- 
phate.    (Compare  Fres.,    Quant.   Anal.,   §  135,  p.  275.) 

Appendix  1.  When  only  the  amount  of  iron  in  an  ore 
is  to  be  determined,  thoroughly  mix  1  gm.  of  the  ore  with 
3  gms.  of  sodium  fluoride,  transfer  to  a  large  platinum 
crucible,  cover  with  12  gms.  of  coarsely  powdered  acid 
sodium  sulphate,  and  fuse  for  20  or  30  minutes.  Then 
cool,  add  concentrated  sulphuric  acid,  fuse  to  a  homo- 
geneous paste,  dissolve  in  water,  reduce  with  zinc  and 
platinum,  and  titrate  with  potassium  permanganate.  As 
stated  before,  titanium,  if  present,  must  first  be  removed. 
(See  Am.  Jour.  Sci.,  XLV.,  178.     Clarke.) 

Appendix  2.  If  titanium  alone  is  to  be  determined,  fuse 
the  ore  in  the  same  way  with  sodium  fluoride  and  acid 


TITANIUM.  85 

sodium  sulphate,  treat  with  sulphuric  acid,  bring  into 
solution,  precipitate  the  ferric  oxide  and  titanium  dioxide, 
and  proceed  to  determine  the  latter,  as  directed  in  Note  7 
of  analysis  of  titaniferous  iron  ore. 

Note. — Instead  of  using  sodium  carbonate  alone  to  effect  the  disintegration  of 
the  ore,  a  mixture  of  sodium  carbonate  with  potassium  carbonate  (both  dry) 
may  be  used.  The  relative  proportions  should  approximate  to  the  ratios  of  the 
respective  molecular  weights),  i.  e.,  106  parts  NaaC08  to  138.2  parts  K,CO|  (11  to 
14  would  be  sufficiently  close). 

If  the  ore  is  very  refractory,  the  flux  proposed  by  Prof.  Dittmar  (Phil.  Soc.  of 
Glasgow)  {Iron,  Jan.,  1876,  p.  131,orDingl.,  Polyt.  Journ.,  CCXXI.,  450)  may  be 
used.  This  is  made  by  fusing  together  3  parts  of  the  above  mixture  of  carbonates 
and  2  parts  of  borax  glass,  over  a  good  Bunsen  burner,  until  the  carbon  dioxide 
has  been  driven  off.  Pour  the  melt  out  upon  a  clean,  cold  surface,  and  when  cool 
pulverize  it  for  use  ;  keep  in  a  tightly  corked  bottle.  Use  5  to  6  parts  of  this 
flux  to  one  of  the  ore,  and  fuse  for  an  hour  or  two  over  a  burner,  stirring  from 
time  to  time  with  a  stout  platinum  wire.  A  small  amount  of  alkaline  nitrate 
may  be  added  to  oxidize  sulphides,  etc.  A  very  high  heat,  such  as  might  be  at- 
tained with  a  blast  lamp,  is  to  be  avoided,  since  that  would  cause  the  borax  to 
attack  the  platinum  of  the  crucible. 

Any  flux  which  may  be  used  should  be  carefully  tested  for  the  presence  of 
sulphates,  when  sulphur  is  to  be  determined  in  the  ore.  If  a  flux  free  from  sul- 
phate cannot  be  obtained,  the  amount  present  must  be  determined  and  a  deduction 
made  accordingly. 

I 


CHAPTER    XV. 

COMPLETE  ANALYSIS   OF  IRON"   OEE. 


Fuse  5  gms.     Note  1. 

Solution  (a). 

Cr3Os,Fe20  ,Al203,P205,Ti02,MnO, 

CaO,MgO,  etc. 


Residue  (a). 

Si02,Ti02,  and  perhaps  Fe208, 

Note  2. 


Add  Na8C03  and  Br.     Note  3. 


Precipitate  (6). 
Fe2,03,Al203,P205,Mn02,Ti02,CaO, 
MgO,  etc. 


Filtrate  (b). 
CrO,.     Note  4. 


Dissolve  in  HC1  and  pass  H2S.     Note  5. 


Filtrate  (c). 
FeO,Al8Ot,P205,Ti02,MnO,CaO,MgO, 
etc. 


Precipitate  (c). 
PtS2,  etc.    Note  5. 


Divide  into  2  portions.     Note  6. 


£  o/  Filtrate  (c). 

FeO,Al808,P206,TiOa,MnO,CaO,MgO, 

etc. 


£  o/  Filtrate  (c). 
Ti02,FeO.     iVbte  7. 


Oxidize  and  precipitate  acetates.     Note  8. 


Precipitate  (d). 
Fe8Os,Al803,P805,Ti02.     Dissolve  in 

HNOs,  dilute  and  divide.    Note  9. 
%  of  Solution   of}£  of  Solution  of 


Precip.  (d) 
P205.    Note  10. 


Precip.  (d). 
Al803,Fe808,Ti08, 
P205.    AddNH4 
HO.    Note  11. 


Filtrate  (d).     , 

MnO,CaO,MgO,  etc.    Concentrate 

and  add  Br.     Note  12. 

Filtrate  (/).     [  Precipitate  (/). 

CaO,MgO.  Note  Mn02.    JVbfe  12. 

13.  | 


Precipitate  (g). 
CaO.    iVbfe  13. 


Filtrate  (g). 
MgO.     iVbte  14. 


S.  in  separate  portion.     Note  15. 

Co,Ni,Zn.    iVbte  16. 

As  in  separate  portion.     Note  17. 

Alkalies  in  separate  portion.     Note  18. 

Copper.     Note  19. 

Water.    Note  20. 

Chlorine,  fluorine,  carbonic  acid,  organic  matter.    Note  21. 

Appendix. 


Iron  ores,  besides  the  ordinary  constituents,   such  as 


DECOMPOSING  THE   OKE.  87 

iron,  alumina,  manganese,  lime,  magnesia,  sulphur,  phos- 
phorus, silica,  and  water,  frequently  contain  titanium, 
zinc,  carbonic  acid,  potassium,  and  sodium,  and  occasion- 
ally chromium,  copper,  nickel,  cobalt,  arsenic,  and  or- 
ganic matter,  and  in  some  rare  cases  vanadium,  tungsten, 
chlorine,  and  fluorine,  besides  other  substances  in  very 
minute  quantities. 

Note  1. — Fuse  5  gms.  of  the  ore,  pulverized  to  impal- 
pable powder  (well  mixed  with  25  gms.  of  anhydrous  sodi- 
um carbonate  and  5  gms.  of  sodium  nitrate),  in  a  capa- 
cious platinum  crucible.  Remove  the  fused  mass  from 
the  crucible  with  as  little  water  as  possible,  allow  the  solid 
matter  to  settle,  decant  off  the  clear  fluid  into  another 
vessel,  digest  the  solid  matter  with  25  or  30  c.  c.  of  strong 
hydrochloric  acid  on  a  water-bath  for  an  hour  or  two, 
renewing  the  acid,  if  necessary,  and  keeping  the  vessel 
covered.  When  all  is  dissolved,  except  perhaps  some  sil- 
ica and  titanium  oxide,  and  no  undecomposed  ore,  add 
the  residue,  together  with  the  clear  fluid,  to  the  first  water 
solution,  and  after  acidifying  with  hydrochloric  acid, 
evaporate  to  dryness  as  usual,  for  the  determination  of 
silica.  Should  there  be  any  undecomposed  ore,  filter  it 
out,  wash  with  water,  and  dry  it.  Add  the  filtrate  to  the 
first  water  solution.  Then  burn  the  filter  and  residue  in  a 
capacious  platinum  crucible,  add  6  or  8  gms.  of  acid 
potassium  sulphate,  and  fuse  for  15  minutes  at  a  tempera- 
ture scarcely  above  the  fusing  point  of  the  latter,  then 
raise  the  heat  somewhat,  so  that  the  bottom  of  the  cru- 
cible may  just  appear  red,  and  keep  it  so  for  15  or  20  min- 
utes. The  fusing  mass  should  not  rise  higher  than  half- 
way up  the  crucible.  The  mass  begins  to  fuse  quietly, 
and  abundant  fumes  of  sulphuric  acid  escape.  At  the 
expiration  of  20  minutes  the  heat  is  increased  as  much  as 
is  necessary  to  drive  out  the  second  equivalent  of  sul- 
phuric acid,  and  even  to  decompose  partially  the  sulphate 
of  iron  and  chromium.  To  the  fused  mass  now  add  4  or 
5  gms.  of  pure  carbonate  of  soda,  heat  to  fusion,  and  add 


8«  IRON   ORE — COMPLETE. 

in  small  portions  from  time  to  time  during  an  hour,  3  or  4 
gms.  of  sodium  nitrate,  maintaining  a  gentle  red  heat  all 
the  while,  then  heat  for  15  minutes  to  bright  redness, 
cool,  and  treat  the  fused  mass  with  hot  water ;  remove  it 
from  the  crucible,  allow  the  solid  matter  to  settle,  add  the 
clear  fluid  to  the  previous  solution,  digest  the  residue 
with  strong  hydrochloric  acid,  as  directed  above,  and  if 
the  ore  is  entirely  decomposed,  add  everything  to  the 
other  fluid.  Should  there  still  be  undecomposed  ore,  re- 
peat the  treatment. 

(See  Fres.,  Quant.  Anal,  §  223,  p.  524.) 

After  entirely  decomposing  the  ore  and  combining  all 
the  solutions,  evaporate  them  to  dryness,  first  on  a  water- 
bath,  and  then  in  an  air-bath,  as  usual  in  the  determina- 
tion of  silica.  When  the  mass  is  thoroughly  dry,  add  10 
c.  c.  of  strong  hydrochloric  acid,  30  c.  c.  of  water,  and 
heat  on  a  water-bath  until  everything  is  dissolved  except 
silica  and  titanium  oxide.  Then  dilute  with  50  or  60 
c.  c.  of  water,  filter,  and  wash  with  about  100  c.  c.  of  5 
per  cent  hydrochloric  acid, 

There  will  be  a  residue  (a)  of  silica  and  titanic  oxide, 
and  a  solution  (a)  of  the  remaining  constituents  of  the 
ore.  Dry  residue  (a),  and  reserve  solution  (a),  to  be  com- 
bined with  the  solution  resulting  from  the  re-fusion  of  the 
silica,  which  always  contains  a  portion  of  the  titanic 
oxide,  and  usually  some  ferric  oxide,  particularly  if  the 
quantity  of  titanic  oxide  in  the  ore  be  large. 

Note  2. — Fuse  residue  (a),  containing  silica  and  titanic 
oxide,  and  perhaps  a  little  ferric  oxide,  with  10  or  12 
times  its  weight  of  acid  sodium  sulphate,  soften  the  mass 
by  heating  it  in  the  crucible  with  concentrated  sulphuric 
acid,  cool  thoroughly,  and  dissolve  in  about  400  c.  c.  cold 
water.  Filter  out  silica,  wash  with  about  100  c.  c.  of  cold 
water,  containing  5  per  cent  of  hydrochloric  acid,  and  add 
filtrate  and  washings  to  solution  (a).  Dry,  ignite,  and 
weigh  the  residue,  which  may  still  contain  some  titanic 
oxide.     Then  treat  with  concentrated  sulphuric  acid  and 


CHROMIUM.  89 

ammonium  fluoride,  adding  a  quantity  of  the  latter  equal 
in  weight  to  about  8  times  that  of  the  silica.  After  evap- 
orating off  the  sulphuric  acid  and  igniting  gently,  cool 
and  weigh.  Then  repeat  the  treatment  until  the  crucible 
ceases  to  lose  weight.  (Compare  Rose's  directions,  in  his 
chapter  on  silicon,  p.  874.)  The  weight  of  the  silica  is 
estimated  from  the  loss. 

Should  there  be  any  residue  left  after  the  treatment 
with  ammonium  fluoride,  fuse  it  with  acid  sodium  sul- 
phate,- in  the  manner  directed  above,  bring  it  into  cold- 
water  solution,  and  add  it  to  solution  (a),  which  will  then 
contain  all  the  constituents  of  the  ore  except  silica. 

Note  3. — To  solution  (a)  add  sodium  carbonate,  until  it 
is  strongly  alkaline,  and  then,  without  filtering  out  the 
precipitate,  bromine  water,  until  it  is  deeply  colored,  stir- 
ring constantly.  After  this,  add  5  or  6  c.  c.  of  pure  bro- 
mine, and  heat  for  an  hour,  with  frequent  stirring,  keep- 
ing it  alkaline  and  gradually  increasing  the  heat  until  the 
solution  boils,  and  continue  to  boil  gently  for  another 
hour.  The  chromic  oxide  will  be  oxidized  to  chromic 
acid.  Then  filter  and  wash  thoroughly  with  hot  water, 
first  by  decantation  3  or  4  times,  boiling  each  time  with 
a  small  amount  of  water,  and  then  on  the  filter,  until  the 
wash-water  runs  through  colorless.  If  there  be  a  large 
amount  of  chromium  in  the  ore,  in  order  to  insure  com- 
plete separation  of  it,  wash  the  mass  on  the  filter  back 
into  a  beaker,  with  about  200  c.  c.  of  water,  and  treat 
again  with  bromine  water  and  2  or  3  c.  c.  of  pure  bro- 
mine, and  proceed  as  before,  filtering  through  the  same 
filter.  This  will  insure  complete  separation  of  the  chro- 
mium from  all  but  traces  of  the  other  constituents  of 
the  ore,  with  the  exception  of  manganese,  which  will  also 
be  found  in  the  filtrate  as  sodium  manganate. 

There  will  be  a  filtrate  (&),  containing  all  the  chromium 
as  alkaline  chromate,  and  a  precipitate  (&),  containing  the 
principal  part  of  the  other  constituents  of  the  ore. 

Note  4. — To  filtrate    (&),  containing  chromium,  man- 


90  IKON   ORE— COMPLETE. 

ganese,  and  traces  of  other  constituents  of  the  ore,  add 
nitric  acid  to  partly  neutralize,  then  3  or  4  gms.  ammo- 
nium nitrate,  and  evaporate  until  no  odor  of  ammonia  is 
perceptible.  Then  dilute  with  100  c.  c.  of  water,  filter,  and 
wash  the  residue  of  manganese  sesquioxide,  silica, 
alumina,  and  titanic  oxide,  dissolve  it  in  hydrochloric 
acid,  after  removing  it  from  the  filter,  with  a  little  water, 
dry  and  burn  the  filter,  and  add  the  ash,  together  with 
the  solution  of  the  residue,  to  the  solution  of  precipitate 
(b),  or  the  principal  solution  of  the  ore.  Into  the  filtrate, 
containing  only  alkaline  chromate,  after  acidifying  it 
with  hydrochloric  acid,  conduct  sulphuretted  hydrogen 
to  saturation  to  reduce  the  chromic  acid  to  sesquioxide. 
Allow  the  sulphur  to  settle  entirely,  filter,  wash,  and  in 
the  filtrate  precipitate  the  chromic  oxide  with  ammonia. 
(SeeFres.,  Quant.  Anal,  §  106,  p.  176.)  Evaporate  the  fil- 
trate from  the  chromium  to  dryness,  ignite  the  residue, 
together  with  the  precipitate  (if  any)  produced  by  sul- 
phuretted hydrogen,  dissolve  any  residue  that  may  be 
left  in  hydrochloric  acid,  and  add  the  solution  to  that  of 
precipitate  (b)  or  the  principal  solution  of  the  ore. 

Note  5. — Dissolve  precipitate  (b)  in  hydrochloric  acid, 
dilute  with  cold  water,  and  saturate  with  sulphuretted 
hydrogen,  filter,  and  wash  with  cold  water.  Do  not  heat, 
as  otherwise  titanic  oxide  may  be  precipitated. 

There  will  be  a  filtrate  (c)  and  a  precipitate  (c)y  which 
latter  may  contain  platinic  sulphide  (due  to  platinum 
takei^  from  the  crucible  by  the  fluxes),  and  also  sulphides , 
of  metals  of  the  higher  groups,  which,  if  present  in 
sufficient  quantity,  are  to  be  determined  by  methods 
which  will  be  explained  later. 

Note  6. — Dilute  filtrate  (c)  to  500  c.  c,  if  it  does  not 
already  exceed  that  volume,  and  divide  it  into  2  portions, 
one  containing  100  c.  c,  or  one  fifth,  and  equivalent  to  1 
gm.  of  ore,  for  the  estimation  of  iron  and  titanium,  and 
another  containing  400  c.  c. ,  or  four  fifths,  and  equivalent 
to  4  gms.  of  ore,  for  the  estimation  of  other  constituents 


TITANIUM.  91 

Should  the  solution  exceed  500  c.  c.  and  be  less  than 
1,000  c.  c.j  dilute  to  the  latter  volume,  and  divide  in  the 
same  proportion.  It  is  not  well  to  concentrate  the  solu- 
tion, by  the  aid  of  heat,  as  some  of  the  titanic  oxide  may 
be  precipitated,  which  will  necessitate  troublesome  steps 
to  bring  it  back  into  solution. 

Note  7. — To  one  fifth  of  filtrate  (c),  representing  1  gm. 
of  the  ore,  add  a  little  potassium  chlorate  and  hydro- 
chloric acid,  and  boil,  in  order  to  oxidize  sulphur,  and  con- 
vert the  ferrous  into  ferric  oxide.  Then  precipitate  the 
ferric  and  titanic  oxides  by  adding  pure  potassium 
hydrate  in  excess,  filter,  and  wash  with  hot  water.  By 
this  means  all  but  traces  of  the  alumina  will  be  held  in  so- 
lution, and  thus  separated  from  the  iron  and  titanium, 
with  the  latter  of  which  it  otherwise  might  afterward  be 
precipitated  by  boiling.  Dissolve  the  precipitate  in  dilute 
sulphuric  acid,  and  increase  the  volume,  by  addition  of 
cold  water,  to  about  500  c.  c.  Then  add  ammonia,  drop 
by  drop,  until  a  permanent  precipitate  is  formed,  and  sul- 
phuric acid,  cautiously,  until  it  is  dissolved,  and  the  solu- 
tion made  slightly  acid.  After  this,  pass  sulphuretted 
hydrogen  until  the  solution  is  colorless,  thus  reducing  the 
ferric  to  ferrous  oxide.  Boil  for  an  hour  or  two,  keeping 
up  the  volume,  by  the  occasional  addition  of  water  con- 
taining sulphuretted  hydrogen  ;  allow  the  precipitate  to 
settle,  filter,  and  wash  with  hot  water.  Dry  the  precipi- 
tate, and  as  some  iron  may,  and  probably  will,  have  been 
precipitated  with  the  titanium,  fuse  with  10  or  12  times  its 
weight  of  acid  sodium  sulphate,  digest  with  concentrated 
sulphuric  acid,  bring  the  mass  into  solution  in  cold  water, 
nearly  neutralize  as  above,  introduce  sulphuretted  hydro- 
gen, and  repeat  the  precipitation  in  the  same  manner  as 
before.  Finally  filter,  wash  well  with  hot  water,  dry, 
ignite,  and  weigh  the  titanic  oxide.  In  igniting  the  pre- 
cipitate, it  is  well,  after  burning  the  filter,  and  igniting 
the  precipitate,  to  cool  the  crucible  a  little,  introduce 
•some  ammonium  carbonate,  heat  moderately,   until  the 


92  IR<m   ORE — COMPLETE. 

carbonate  is  volatilized,  and  then  intensely,   in  order  to 
expel  the  last  traces  of  sulphuric  acid. 

Concentrate  the  nitrates  and  washings,  after  adding  a 
little  hydrochloric  acid  and  potassium  chlorate  to  about 
200  c.  c,  precipitate  ferric  hydrate  with  ammonia,  filter, 
wash  well  with  hot  water,  dissolve  the  precipitate  in  hot 
dilute  sulphuric  acid,  boil  for  some  time  to  expel  chlorine, 
add  water,  introduce  into  bottles,  reduce  with  amalga- 
mated zinc  and  platinum,  and  determine  the  iron  by  po- 
tassium permanganate,  as  directed  in  analysis  of  ammonia- 
iron-alum. 

Note  8. — To  four  fifths  of  filtrate  (c),  representing  4  gms. 
of  ore,  add  a  little  potassium  chlorate,  and  boil,  to  oxidize 
the  ferrous  oxide,  nearly  neutralize  with  sodium  carbonate, 
add  about  10  gms.  of  sodium  acetate,  and  a  few  drops  of 
acetic  acid,  dilute  to  2.5  litres,  in  a  large  flask,  and  heat  to 
boiling.  Continue  the  boiling  for  about  5  minutes,  remove 
the  heat,  allow  the  precipitate  of  basic  acetates  to  settle, 
and  filter  as  rapidly  as  possible,  keeping  the  fluid  hot 
while  doing  so.  Should  there  be  much  manganese  in  an 
ore,  it  is  well  to  dissolve  the  acetates  in  hydrochloric  acid, 
and  re-precipitate,  by  the  same  method,  as  in  such  a  case, 
the  acetates  are  apt  to  carry  with  them  a  small  quantity  of 
manganese,  when  the  fluid  contains  much. 

If  the  oxidation  of  the  ferrous  oxide,  by  boiling  with 
potassium  chlorate,  has  not  been  complete,  the  red  modifi- 
cation of  ferric  oxide  will  be  precipitated,  giving  a  great 
deal  of  trouble,  as  it  is  apt  to  run  through  the  filter,  and  is 
very  insoluble.  Generally,  the  danger  can  be  detected  in 
time  to  be  avoided,  by  the  appearance  of  the  precipitate 
caused  by  the  sodium  carbonate,  used  in  preparing  the 
solution  for  the  precipitation  of  acetates.  If  the  oxidation 
of  the  ferrous  oxide  has  been  incomplete,  the  precipitate, 
instead  of  having  the  ordinary  reddish-brown  color,  will 
be  very  dark  (nearly  black).  In  such  a  case,  acidify  with 
hydrochloric  acid,  add  more  potassium  chlorate,  boil  for  a 
short  time,  and  precipitate  the  acetates  as  directed  above. 


PHOSPHORUS — ALUMINA.  93 

Note  9. — Dissolve  the  basic  acetates,  or  precipitate  (d), 
in  nitric  acid,  by  transferring  the  precipitate  (a  little  at  a 
time)  from  the  filter  to  the  acid,  previously  heated  in  a 
medium-sized  beaker,  stirring  until  the  precipitate  goes 
into  solution.  When  all  that  can  be  conveniently  removed 
from  the  filter  is  dissolved,  warm  the  solution,  and  pour  it 
back  on  the  filter,  to  dissolve  the  portion  adhering  to  it, 
and  wash  the  filter  thoroughly.  Dilute  the  filtrate  to  400 
c.  c,  and  divide  into  2  portions,  one  of  300  c.  c,  for  the  de- 
termination of  phosphoric  acid,  and  another  of  100  c.  c, 
for  that  of  alumina. 

Note  10. — In  three  fourths  of  solution  of  precipitate  {d\ 
containing  300  c.  c,  and  representing  3  gms.  of  ore,  de- 
termine phosphoric  acid  as  directed  in  partial  analysis  of 
iron  ore  by  first  method. 

Note  11. — In  one  fourth  of  the  solution  of  precipitate 
•(d),  containing  100  c.  c,  and  representing  1  gm.  of  ore, 
precipitate  the  alumina,  ferric  hydrate,  phosphoric  acid, 
and  titanic  oxide  together,  by  means  of  ammonia  in  ex- 
cess. (See  analysis  of  potassium  alum.)  From  the  per- 
centage value  of  this  precipitate,  deduct  that  of  ferric 
oxide,  phosphoric  acid,  and  titanic  oxide,  found  elsewhere 
in  the  analysis.  The  difference  will  give  the  per  cent  of 
alumina. 

A  direct  determination  of  the  alumina  may  be  made  by 
fusing  the  ignited  precipitate  with  acid  sodium  sulphate, 
digesting  the  fused  mass  with  sulphuric  acid,  dissolving 
in  water,  addiug  an  excess  of  pure  potassium  hydrate,  and 
warming.  By  this  means,  the  titanic  oxide  and  the  ferric 
oxide  (carrying  the  phosphoric  acid  with  it)  will  be  precip- 
itated, while  the  alumina  will  remain  in  solution.  If,  now, 
the  solution  be  filtered,  acidified  with  "hydrochloric  acid, 
and  then  made  alkaline  with  ammonia,  and  boiled,  the 
alumina  will  be  precipitated,  and  can  be  determined. 
(Fres.,  Quant.  Anal.,  §  160,  p.  361.)  Or,  fuse  the  ignited 
precipitate  in  a  silver  crucible  with  potassium  hydrate, 
l)oil  the  mass  with  water,  filter  the  alkaline  fluid  contain- 


94  IR<m   ORE — COMPLETE. 

ing  the  alumina  from  the  undissolved  titanic  oxide,  ferric- 
oxide,  and  phosphoric  acid,  acidify  the  nitrate  with  hydro- 
chloric acid,  and  precipitate  the  alumina  with  ammonium 
carbonate.  (H.  Rose,  Quant.  Anal.,  chapter  on  Alumina, 
p.  149.) 

Note  12. — Concentrate  filtrate  (d),  or  nitrate  from  the 
acetates,  to  100  c.  c,  if  possible,  and  precipitate  the  man- 
ganese, by  adding  a  sufficient  quantity  of  bromine,  and 
heating.  Filter  out  the  manganese  dioxide  or  precipitate 
(f\  wash  it  moderately  with  hot  water,  transfer  it  with 
the  filter  (without  drying)  to  a  very  small  beaker,  press 
down  the  filter  upon  the  bottom  of  the  beaker  with  a  glass 
rod,  add  enough  concentrated  hydrochloric  acid  to  cover 
the  precipitate,  and  heat.  When  the  manganese  dioxide 
is  dissolved,  dilute  with  20  or  30  c.  c.  of  water,  filter,  and 
wash  thoroughly.  Heat  the  filtrate  nearly  to  boiling,  add 
excess  of  sodium  carbonate,  boil  out  free  carbonic  acid, 
filter  out  the  manganese  carbonate,  wash  with  hot  water, 
dry,  ignite  the  carbonate  to  tri-mangano  tetroxide,  and 
calculate  the  sesquioxide.  (See  analysis  of  manganese 
ore.) 

Note  13. — To  filtrate  (f)  from  the  precipitate  of  manga- 
nese dioxide,  add  ammonia  until  it  is  slightly  alkaline, 
then  a  sufficient  quantity  of  ammonium  oxalate.  Boil, 
and  allow  the  precipitate  to  settle  completely.  Pour  the 
clear  fluid  through  a  filter,  add  to  the  precipitate  20  or  30 
c.  c.  hot  water,  stir,  and  allow  it  to  settle.  Again  pour 
the  clear  fluid  through  the  filter.  Then  dissolve  the  pre- 
cipitate in  the  beaker  with  hot  dilute  hydrochloric  acid, 
add  to  the  solution  4  or  5  c.  c.  of  ammonium  oxalate,  and 
make  it  alkaline  with  ammonia.  Finally,  filter  into  a 
fresh  beaker,  and  wash  thoroughly  with  hot  water.  Dry 
the  precipitate  of  calcium  oxalate,  transfer  it  to  a  weighed 
crucible,  moisten  it  with  concentrated  sulphuric  acid, 
evaporate  off  the  excess  of  acid,  ignite,  and  weigh  the 
calcium  sulphate,  and  calculate  the  per  cent  of  lime. 
(Consult  analysis  of  calcium  carbonate.) 


MAGNESIA — SULPHUK.  95 

Note  14. — Concentrate  the  second  filtrate,  or  the  filtrate 
from  the  re-precipitated  calcium  oxalate  to  small  bulk  (after 
acidifying  it  with  hydrochloric  acid),  make  it  alkaline 
with  ammonia,  and  add  it  to  the  first  filtrate  from  the  cal- 
cium oxalate.  (Consult  analysis  of  limestone,  andFres., 
Quant  Anal.,  §  154.6,  p.  349.) 

The  combined  filtrates  constitute  filtrate  {g).  To  this, 
if  not  already  alkaline,  add  ammonia  and  a  sufficient 
quantity  of  hydro-disodium  phosphate,  and  allow  to  stand 
in  the  cold  for  some  hours.  When  the  precipitate  of  mag- 
nesium phosphate  has  entirely  settled,  filter,  wash  with 
dilute  ammonia,  dry,  ignite,  and  weigh  the  magnesium 
pyrophosphate,  and  calculate  the  magnesia. 

Owing  to  the  quantity  of  ammonium  chloride  and  other 
salts  introduced  into  the  analysis,  by  the  re-agents  used, 
it  may  be  impossible  to  precipitate  the  magnesia  com- 
pletely. It  is  advisable,  therefore,  to  treat  the  filtrate 
from  the  magnesium  phosphate  by  one  of  the  methods 
prescribed  in  the  analysis  of  limestone,  to  recover  any 
magnesia  which  may  have  been  held  in  solution. 

Note.  15 — In  iron  ores  containing  titanium  and  requir- 
ing the  use  of  sulphates,  it  is,  of  course,  impossible  to 
determine  the  sulphur  in  the  current  analysis.  In  such 
cases  it  is  necessary  to  determine  it  in  a  separate  portion  of 
ore.  A  very  good  method  of  fusion  for  this  purpose  is  one 
devised  by  Hart,  for  the  decomposition  of  chromic  iron 
ore  (Chem.  Gaz.,  1855,  p.  458),  and  quoted  by  Fresenius, 
in  his  Quantitative  Analysis,  4th  London  edition,  §  160 : 
' '  Fuse  8  parts  of  borax  in  a  platinum  crucible,  add  to  the 
mass  in  fusion  1  part  by  weight  of  the  finely  pulverized 
ore,  stir  constantly,  and  keep  the  crucible  half  an  hour 
longer  at  a  bright  red  heat ;  add  dry  sodium  carbonate  as 
long  as  it  causes  effervescence,  then  gradually,  and  with 
frequent  stirring  with  a  platinum  wire,  3  parts  of  a  mix- 
ture of  equal  parts  of  potassium  nitrate  and  sodium 
carbonate,  and  keep  the  mass  a  few  minutes  longer  in 
fusion."     Remove  the  mass  from  the  crucible  with  water, 


96  IRON   OEE — COMPLETE, 

dissolve  in  hydrochloric  acid,  and  determine  sulphur,  as 
in  partial  analysis  of  iron  ore.     (See  note  on  p.  85.) 

Note  \  6. — If  zinc,  nickel,  and  cobalt  are  present,  they 
will  be  found  in  filtrate  (d)  (or  the  acetic  acid  solution, 
after  removing  the  acetates),  together  with  the  manganese, 
lime,  and  magnesia.  The  best  method  for  separating  the 
nickel,  cobalt,  and  zinc  from  the  others,  is  that  suggested 
by  Gibbs,  in  the  Am.  Jour,  of  Sci.  and  Arts,  Jan.  7, 
1865:  Add  a  few  drops  of  acetic  acid  to  the  solution, 
boil,  pass  a  rapid  current  of  sulphuretted  hydrogen  for 
half  an  hour,  and  continue  the  boiling  while  doing  so. 
Gibbs  states  that  every  trace  of  nickel,  cobalt,  and  zinc 
will  be  precipitated  as  sulphides,  while  the  whole  of  the 
manganese  (as  well  as  the  lime  and  magnesia)  remains  in 
solution.  These  are  to  be  determined  as  directed  in  notes 
12,  13,  and  14.  If  large  quantities  of  manganese  and  zinc 
be  present,  as  in  the  case  of  Franklinite  ores,  it  is  well  to 
dissolve  the  precipitated  sulphides,  and  after  adding  a 
sufficient  quantity  of  sodium  acetate  and  acetic  acid, 
repeat  the  precipitation  as  above,  as  some  manganese  may 
be  precipitated  with  the  zinc.  The  writer  has  had  it  to 
occur  in  the  analysis  of  Franklinite.  Under  ordinary  cir- 
cumstances, the  re-precipitation  is  unnecessary.  Dissolve 
the  precipitated  sulphides  in  aqua  regia,  convert  the 
metals  into  double  cyanides,  by  means  of  pure  potassium 
cyanide,  and  precipitate  the  zinc  by  potassium  sulphide, 
as  recommended  by  Wohler.  (See  analysis  of  German 
silver.)  In  the  filtrate  from  the  zinc,  determine  the 
nickel  and  cobalt  as  directed  in  the  analysis  of  nickel 
ore. 

Note  17. — Fuse  2  or  3  gms.  of  the  ore  with  10  times  the 
weight  of  a  mixture  of  equal  parts  of  sodium  carbonate 
and  nitrate,  extract  the  sodium  arsenate  by  boiling  with 
water,  filter,  acidulate  the  alkaline  filtrate  with  hydro- 
chloric acid,  and  precipitate  the  arsenic  with  sulphuretted 
hydrogen.  Dissolve  the  sulphide  by  digesting  with  hydro- 
chloric acid  and  potassium  chlorate,  make  the  solution 


COPPER — WATER,    ETC. — APPENDICES.  97 

alkaline  with,  ammonia,   and  determine  the  arsenic,  as 
directed  in  the  analysis  of  arsenic  ore. 

Note  18. — To  determine  sodium  and  potassium,  fuse 
1  gm.  with  precipitated  calcium  carbonate  and  ammonium 
chloride,  and  proceed  as  directed  in  analysis  of  feldspar, 
bj  J.  Lawrence  Smith' s  method. 

Note  19. — If  the  ore  contain  copper  in  considerable 
quantity,  it  may  be  determined  in  precipitate  (c),  or,  if 
the  quantity  be  very  small,  in  a  larger  and  separate  por- 
tion of  ore,  by  methods  described  in  analysis  of  copper  ore. 

Note  20. — Water  existing  in  the  ore  as  mere  hygro- 
scopic moisture,  is  determined  by  drying  2  or  3  gms.  of  the 
finely  powdered  ore  to  constant  weight  at  a  temperature 
of  about  110°  C. 

If  the  water  be  a  constituent  part  of  the  ore,  as  in  the 
case  of  limonite,  determine  it,  as  directed  in  analysis  of 
hydro-disodium  phosphate. 

Note  21. — For  the  determination  of  chlorine,  fluorine, 
carbonic  acid,  and  organic  matter,  consult  analysis  of 
limestone. 

Appendix  1. — Analysis  of  iron  ore  containing  titanium, 
but  no  chromium : 

Fuse  5  gms.  of  the  finely  powdered  ore  with  25  gms.  of 
sodium  carbonate,  and  5  gms.  of  sodium  nitrate,  and  treat 
the  fused  mass  as  directed  in  Note  1.  Follow  the  direc- 
tions given  in  the  same  note  for  effecting  complete  decom- 
position of  the  ore,  and  for  filtering,  washing,  and  drying 
residue  (a). 

There  will  be  a  solution  (a)  and  a  residue  (a).  Treat 
residue  (a)  as  directed  in  Note  2.  Omit  the  treatment  of 
solution  (a)  with  sodium  carbonate  and  bromine,  as 
directed  in  Note  3,  pass  sulphuretted  hydrogen  through 
solution  (a),  and  proceed  as  directed  in  Note  5  for  the 
treatment  of  the  solution  of  precipitate  (b).  The  rest  of 
the  analysis  is  made  in  the  same  manner,  as  that  of  iron 
ores  containing  chromium  as  well  as  titanium. 

Appendix  2. — Analysis  of  iron  ore  containing  neither 
titanium  nor  chromium : 


98  IKON   OEE — COMPLETE. 

Fuse  5  gms.  of  the  ore  with  sodium  carbonate  and 
nitrate,  and  proceed  as  directed  in  Note  1  for  the  treat- 
ment of  the  fused  mass.  Probably,  if  the  ore  has  been 
properly  pulverized,  there  will  be  no  undecomposed  ore. 
Should  there  be  any,  dry  and  ignite  the  residue,  and  fuse 
it  again  with  sodium  carbonate  and  nitrate,  and  not  with 
sulphate,  as  otherwise  it  will  be  necessary  to  determine 
the  sulphur  in  a  separate  portion  of  ore. 

There  will  be,  as  in  the  analysis  of  titaniferous  iron  ore 
containing  chromium,  a  solution  (a)  and  a  residue  (a). 

Dry,  ignite,  and  weigh  residue  (a),  expel  the  silica  with 
ammonium  fluoride  and  sulphuric  acid,  and  estimate  the 
per  cent  of  silica  by  the  loss  of  weight.  Should  there  be 
any  residue  left  in  the  crucible,  it  will  be  entirely  ferric 
oxide.  Bring  it  into  solution  as  directed  in  Note  2,  by 
fusion  with  sodium  sulphate.  Divide  this  solution  into  2 
parts,  one  of  one  fifth,  and  another  of  four  fifths.  From 
the  part  containing  one  fifth,  precipitate  the  ferric  hydrate 
by  ammonia,  filter,  dissolve  the  precipitate  in  sulphuric 
acid,  and  combine  the  solution  with  that  of  the  ferric  hy- 
drate obtained  from  one  fifth  of  solution  (a).  Add  the 
part  containing  four  fifths  to  four  fifths  of  solution  (a). 
Omit  the  treatment  of  solution  (a)  with  sodium  carbon- 
ate and  bromine  (as  directed  in  Note  3),  and  at  once  divide 
it  into  two  parts,  one  of  one  fifth  for  iron  and  sulphur, 
and  another  of  four  fifths  for  the  determination  of  the  other 
constituents  of  the  ore.  In  the  part  containing  one  fifth, 
precipitate  the  ferric  hydrate  by  ammonia,  filter  it  out, 
dissolve  it,  together  with  the  small  precipitate  obtained 
from  one  fifth  of  the  residue  left  in  the  crucible  after  ex- 
pelling silica,  and  determine  the  iron  as  usual,  by  titration 
with  potassium  permanganate.  In  the  filtrate  from  the 
precipitate  of  ferric  hydrate,  in  one  fifth  of  solution  (a), 
determine  the  sulphur.     (See  partial  analysis  of  iron  ore.) 

Through  the  portion  of  solution  (a)  containing  four 
fifths  (combined  with  four  fourths  of  the  solution  of  the 
residue  left  after  expelling  silica),  pass  sulphuretted 
hydrogen.     (See  Note  5.)    Then  oxidize  the  filtrate,  and 


VANADIUM — TUNGSTEN.  99 

proceed  as  directed  in  Note  8.  After  this,  continue  the 
analysis,  as  directed  for  that  ore,  containing  both 
chromium  and  titanium. 

Appendix  3. — Vanadium  and  tungsten  have  been  found 
in  iron  ores. 

To  determine  vanadium,  fuse  15  or  20  gms.  of  the  ore,  in 
the  form  of  impalpable  powder,  with  one  third  its  weight 
of  potassium  nitrate.  Then  cool,  and  remove  the  mass 
from  the  crucible  by  digesting  with  water  as  usual,  and 
mix  carefully  with  nitric  acid,  leaving  the  solution  slight- 
ly alkaline.  Filter,  and  add  to  the  filtrate  barium 
chloride  as  long  as  it  produces  a  precipitate.  Filter  out 
the  baryta  salts  ;  to  the  still  moist  precipitate  add  dilute 
sulphuric  acid  in  slight  excess,  boil  and  filter.  Then  neu- 
tralize the  filtrate  with  ammonia,  concentrate,  and  add  a 
fragment  of  ammonium  chloride.  As  the  ammonium 
chloride  dissolves,  ammonium  vanadate  is  precipitated,  as 
a  crystalline  powder.  Allow  it  to  settle,  filter  it  out,  and 
wash  it  with  solution  of  ammonium  chloride.  Dry  the 
precipitate,  and  heat  it  to  red  vanadic  acid,  which  fuses, 
and  cools  to  a  crystalline  mass.  (H.  Rose,  Quant.  Anal., 
pp.  498,  et  sea.) 

To  determine  tungsten,  fuse  15  or  20  gms.  of  the  finely 
pulverized  ore  with  four  times  its  weight  of  sodium  carbon- 
ate. (Do  not  use  nitrate.)  Digest  the  fused  mass  with 
water,  filter,  and  wash.  Saturate  the  solution  carefully 
with  nitric  acid,  so  that  it  will  slightly  redden  litmus 
paper,  after  the  carbonic  acid  has  been  expelled.  Let  it 
stand  24  hours  in  a  moderately  warm  place,  and  then,  but 
not  before,  add  solution  of  mercurous  nitrate  as  long  as  it 
produces  a  precipitate.  Let  the  precipitate  settle,  collect 
it  on  a  filter,  and  wash  with  water,  to  which  has  been 
added  a  little  mercurous  nitrate.  This  is  necessary  to  pre- 
vent the  liquor  from  running  through  the  filter  turbid. 
After  drying,  burn  the  precipitate  under  a  chimney  with  a 
good  draught.  After  calcination,  tungstic  acid  remains 
pure.  Repeat  the  ignition  to  constant  weight.  (See  H* 
Rose,  Quant.  Anal.,  p.  488.) 


CHAPTER  XVI. 

SLAG. 

Fuse  5  gms.  of  the  finely-pulverized  slag  with  25  gms. 
of  anhydrous  sodium  carbonate  and  2  gms.  of  sodium 
nitrate,  and  proceed  to  the  determination  of  the  silica,  as 
in  the  analysis  of  feldspar. 

Dilute  the  filtrate  from  the  silica,  with  water,  to  500  c.  c, 
and  divide  it  into  2  portions,  one  of  100  c.  c,  and  equiva- 
lent to  1  gm.  of  the  slag ;  the  other  of  400  c.  c,  and  equiv- 
alent to  4  gms. 

In  the  portion  containing  100  c.  c,  precipitate  the  ferric 
oxide  with  ammonia,  filter  and  wash  out  all  sulphuric  acid, 
dissolve  the  precipitate  in  hot  dilute  sulphuric  acid,  trans- 
fer to  bottles,  reduce  with  zinc  and  platinum,  titre  with 
standardized  potassium  permanganate,  determine  the  iron 
and  calculate  it  to  ferrous  oxide.  Acidify  the  filtrate  from 
the  precipitate  of  ferric  oxide  slightly  with  hydrochloric 
acid,  and  determine  the  sulphur,  as  in  the  analysis  of 
magnesium  sulphate. 

Saturate  the  portion  containing  400  c.  c.  with  sulphu- 
retted hydrogen,  filter,  wash  well  with  water,  and  deter- 
mine any  metals  that  may  be  present,  by  the  methods 
given  in  their  respective  analyses^  with  the  exception  of 
platinum,  a  small  quantity  of  which  may  be  introduced 
into  the  analysis  by  the  action  of  the  fluxes  on  the  cru- 
cible. 

Boil  the  filtrate  from  the  precipitate  produced  by  sul- 
phuretted hydrogen,  with  about  0.500  gm.  of  potassium 
chlorate,  to  oxidize  sulphur  of  the  sulphuretted  hydrogen, 
and  raise  the  ferrous  to  ferric  oxide,  and  continue  to  boil 
until  free  chlorine  is  expelled.  Then  add  saturated  solu- 
tion of  sodium  carbonate  until  the  fluid  is  slightly  alka- 
line, acidify  it  with  acetic  acid,  and  boil  to  precipitate 


101 

basic  acetates.  (See  analysis  of  manganese  ore.)  Heat  15 
or  20  c.  c.  of  nitric  acid  in  a  beaker,  and  by  means  of  a 
spatnla  add  to  it  the  precipitate  of  acetates  (a  little  at  a 
time),  with,  frequent  stirring.  When  all  that  can  be  con- 
veniently reached  by  the  spatula  is  removed,  pour  the  hot 
solution  through  the  filter,  and  wash  it  well.  Dilute  the 
solution  to  400  c.  c,  and  divide  it  into  2  portions,  one  of 
100  c.  c,  and  the  other  of  300. 

In  the  portion  containing  300  c.  c,  and  equivalent  to  3 
gms.  of  slag,  determine  the  phosphoric  acid,  as  in  analysis 
of  iron  ore  by  the  first  method,  if  the  quantity  of  iron 
present  be  small,  or  by  the  second  method,  if  it  be  large. 

In  the  portion  containing  100  c.  c,  and  equivalent  to  1 
gm.  of  slag,  precipitate  alumina,  ferric  oxide,  and  phos- 
phoric acid  together,  b\  means  of  ammonia,  and  proceed 
as  in  the  analysis  of  pota  ssium  alum . 

From  the  weight  of  this  precipitate,  after  ignition, 
deduct  the  sum  of  the  weights  of  phosphoric  acid  and 
ferric  oxide,  found  previously.  The  difference  will  be  the 
weight  of  the  alumina. 

Concentrate  the  filtrate  from  the  basic  acetates  to  small 
volume,  precipitate  with  bromine,  and  determine  the  man- 
ganese as  in  the  analysis  of  manganese  ore.  Calculate  the 
manganese  to  manganous  oxide. 

In  the  filtrate  from  the  precipitate  of  manganic  oxide, 
determine  the  lime  and  magnesia  as  in  the  analysis  of 
limestone. 

Determine  alkalies  as  in  the  analysis  of  feldspar. 


CHAPTER  XVII. 

CAST-IRON,    STEEL,    AND   WROUGHT-IRON. 

The  analysis  of  cast-iron  covers  the  ground  entirely,  as 
the  constituents  of  steel  and  wrought-iron  are  determined 
in  the  same  manner  as  those  of  cast-iron.  A  large  number 
of  substances  may  be  found  in  the  iron,  either  combined 
or  mixed  with  it.  Those  usually  determined  in  cast-iron 
are  combined  carbon  (or  carbon  chemically  combined  with 
iron),  uncombined  carbon  (or  carbon  existing  in  the  form 
of  graphite),  silicon,  phosphorus,  sulphur,  manganese, 
and  copper.  Besides  these,  the  iron  may  contain  nitro- 
gen, potassium,  sodium,  lithium,  calcium,  magnesium, 
aluminium,  chromium,  titanium,  zinc,  cobalt,  nickel, 
tin,  arsenic,  antimony,  vanadium,  molybdenum,  barium, 
slag,  and,  in  rare  cases,  traces  of  other  metals.  Iron  is 
usually  estimated  by  difference,  that  is,  the  difference 
between  100  and  the  sum  of  the  per  cents  of  the  other 
substances  found.  In  many  cases,  however,  it  is  neces- 
sary to  determine  it  directly.  Owing  to  the  large  number 
of  substances  that  may  be  found  in  cast-iron,  it  is  better 
to  make  the  analysis  on  a  number  of  separate  portions,  to 
avoid  complexity. 

For  the  determination  of  iron,  barium,  and  titanium, 
weigh  10  gms.  of  the  material  in  the  form  of  borings, 
filings,  or  chips,  transfer  to  a  capacious  casserole,  cover 
with  a  convex  glass,  add  300  c.  c.  of  water,  containing  30 
c.  c.  of  concentrated  sulphuric  acid,  heat  on  a  water-bath 
until  the  iron  is  dissolved,  remove  the  cover,  and  heat 
over  a  burner  until  copious  fumes  of  sulphuric  acid  are 
evolved.  Cool,  dilute  with  about  200  c.  c.  of  cold  water, 
filter,  and  wash  with  about  the  same  quantity  of  cold 
water.  Dry  the  residue  (which  may  contain  graphitic 
carbon,  iron,  barium,  and  titanium,  besides  silica),  ignite 


IRON — BARIUM — TITANIUM.  103 

it,  together  with,  the  filter,  in  a  platinum  crucible,  add  7 
or  8  gms.  of  sodium  carbonate  and  3  or  4  of  sodium 
nitrate,  and  fuse  over  a  Bunsen  burner,  until  the  contents 
of  the  crucible  are  fluid.  By  this  means  the  carbon  will 
be  consumed.  Then  remove  the  fused  mass  from  the  cru- 
cible with  water,  acidulate  with  hydrochloric  acid,  add  8 
or  10  drops  of  sulphuric  acid,  and  evaporate  to  dryness, 
as  usual,  for  silica.  To  the  dry  mass  add  about  1  c.  c.  of 
concentrated  sulphuric  acid,  and  40  or  50  c.  c.  of  water, 
filter  out  and  thoroughly  wash  the  silica,  which  may  con- 
tain barium  sulphate  and  titanic  oxide,  and  add  the  fil- 
trate to  the  principal  solution,  which  will  now  contain  all 
the  iron  and  tlie  larger  part  of  the  titanium.  Dry  the  sili- 
ceous residue,  treat  it  with  acid  sodium  sulphate  and  sul- 
phuric acid,  as  directed  in  "  complete  analysis  of  iron 
ore,"  Note  2,  dissolve  in  cold  water,  filter,  wash  thor- 
oughly with  cold  water,  and  add  the  filtrate  to  the  princi- 
pal solution,  which  will  now  contain  all  the  iron  and  titan- 
ium, while  the  residue  will  contain  silica  and  barium. 
Dry  the  residue,  ignite  it  in  a  platinum  crucible,  cool,  and 
weigh.  Expel  the  silica  withv  ammonium  fluoride  and 
sulphuric  acid.  The  loss  will  be  silica.  Determine  it  as  a 
check.  Fuse  the  residue  with  sodium  carbonate,  digest 
the  fused  mass  with  hot  water,  transfer  it  to  a  filter,  and 
wash  with  hot  water,  until  the  sodium  sulphate  and  excess 
of  flux  is  washed  out.  The  barium  will  remain  on  the 
filter  as  carbonate.  Dissolve  it  through  the  filter  with 
dilute  hydrochloric  acid,  precipitate  barium  sulphate  as 
usual,  and  calculate  the  barium. 

Precipitate  the  ferric  and  titanic  oxides  with  pure  potas- 
sium hydrate,  and  proceed  to  determine  the  titanium  as 
directed  in  Note  7  of  "  complete  analysis  of  iron  ore." 

Treat  the  filtrate  as  directed  in  the  same  note,  and  in 
one  tenth  determine  the  iron  by  titration  with  potassium 
permanganate,  as  usual. 

If  no  titanium  be  present,  the  determination  of  iron 
may  be  made  on  1  gm.,  which  is  to  be  treated  in  the  man- 


104  CAST-IKON,    STEEL,    ETC. 

ner  directed  above,  with  the  exception  of  the  steps  taken 
for  the  separation  of  titanium.  Of  course,  the  treatment 
for  the  determination  of  barium  will  be  unnecessary. 

The  presence  of  hydrocarbons  in  the  solution  renders  it 
impossible  to  determine  iron  accurately  with  potassium 
permanganate.  Consequently,  it  is  advisable,  even  after 
evaporating  to  fumes  of  S03,  as  above,  to  precipitate  the 
f  eriic  hydrate,  wash  it  well,  and  re-dissolve  it  in  sulphuric 
acid. 

A  great  many  methods  for  the  determination  of  carbon 
in  iron  and  steel  have  been  proposed  and  used,  of  which 
only  a  few  can  be  noticed  here.  Usually,  all  that  is  re- 
quired to  be  known  is  the  total  amount  of  carbon.  In 
iron  and  steel  containing  no  graphite  this  is  all  combined. 

Where  the  per  cent  of  carbon  present  in  both  conditions 
(that  is,  as  combined  with  the  iron  as  carbide  and  uncom- 
bined  or  graphitic)  is  required,  the  total  carbon  is  deter- 
mined in  one  portion  of  the  iron,  and  the  graphite  in 
another.  The  difference  between  the  amount  of  total 
carbon,  and  that  of  the  graphite,  gives  the  amount  of 
combined  carbon. 

To  determine  total  carbon,  Weyl  dissolves  a  piece  of  the 
iron,  previously  weighed,  suspended  in  dilute  hydro- 
chloric acid,  by  means  of  platinum  pincers,  or  wire,  from 
the  positive  pole  of  a  weak  galvanic  battery  (1  Bunsen 
element),  the  platinum  foil  forming  the  negative  electrode 
being  also  immersed  in  the  fluid.  The  strength  of  the  cur- 
rent is  regulated  by 'increasing  or  diminishing  the  distance 
between  the  piece  of  iron  or  steel  and  the  platinum  foil, 
which  form  the  two  electrodes.  No  ferric  chloride  should 
be  formed.  Should  it  be,  it  can  be  detected  by  the 
yellowish  color  of  the  solution  descending  from  the  iron. 
To  prevent  this,  the  distance  between  the  electrodes  is  in- 
creased. When  a  sufficient  quantity  of  the  iron  has  been 
dissolved,  which  will  require  10  or  12  hours,  the  carbon  is 
removed  from  the  undissolved  portion  of  the  iron,  by 
brushing  it  off  and  washing  it  into  the  solution.     The  lumpK 


TOTAL   CARBON.  105 

of  iron  is  then  dried  and  weighed,  and  the  quantity  taken 
determined  by  the  loss  of  weight.  The  carbon  is  then  col- 
lected in  a  funnel,  the  neck  of  which  is  lightly  plugged 
with  a  little  ignited  asbestos,  washed  moderately  with  water, 
dried,  mixed  with  copper  oxide,  and  burned  in  a  current 
of  oxygen  gas.  The  resulting  carbonic  acid  is  absorbed  in 
soda-lime,  and  the  carbon  calculated.  (See  Fres.,  Quant. 
Anal.,  %  229,  p.  536,  and  also  Crookes's  Select  Methods, 
p.  76.)  For  the  method  of  making  the  combustion,  see 
"  Sugar  (Ultimate  Analysis)." 

Weyl's  method  is  applicable  to  the  determination  of 
carbon  in  hard  iron,  that  cannot  be  readily  broken  into 
small  fragments,  or  be  reduced  to  powder,  by  the  drill 
or  file.  As  carbon  is  sometimes  carried  by  the  mechanical 
working  of  the  current,  particularly  in  the  case  of  steel, 
from  the  positive  to  the  negative  electrode,  it  is  prudent 
to  interpose  a  diaphragm  of  bladder  or  parchment  paper. 

Regnault's  method,  for  which  consult  Fres.,  Quant. 
Anal.,  4th  London  Ed.,  §  249 ;  and  Boussingault's,  for 
which  see  Crookes'  s  Select  Methods,  p.  77,  can  be  used  only 
in  the  case  of  iron  that  is  susceptible  of  being  reduced  to 
a  state  of  very  fine  division. 

R.  E.  Rogers  and  Wm.  B.  Rogers  proposed  the  use  of 
copper  sulphate  to  dissolve  the  iron,  and  the  oxidation  of 
the  residual  carbon  by  means  of  potassium  bichromate  and 
sulphuric  acid,  absorbing  the  resulting  carbonic  acid  in 
soda-lime  or  potassium  hydrate.  (See  Am.  Jour.  Sci.  and 
Arts,  1848.) 

Ullgren  afterward  proposed  the  same  method,  using 
chromic  acid  instead  of  potassium  bichromate.  (See  Fres., 
Quant.  Anal.,  4th  London  Ed.,  §  249.) 

In  a  paper  published  in  the  Chemical  News  of  May, 
1869,  Arthur  Elliott  proposed  a  modification  of  Rogers's 
and  Ullgren' s  methods.  His  process  is  among  the  best  in 
use.  It  has  given  very  satisfactory  results,  in  a  great 
many  analyses,  made  by  the  writer,  of  iron,  steel, 
graphite,  and  coal  of  various  kinds.     For  a  few  experi- 


106 

ments,  giving  the  time  occupied  and  the  per  cent  of 
carbon  obtained,  by  this  method,  and  combustion  in 
oxygen,  see  a  paper  published  by  the  writer  in  the  Am. 
Chemist  of  October,  1871. 

Add  to  2  or  3  gms.  of  borings,  filings,  or  very  small 
fragments  (in  a  small  beaker)  50  c.  c.  of  a  solution  of  neu- 
tral copper  sulphate  (containing  1  part  of  the  salt  in  5 
parts  of  water),  and  heat  gently  for  about  ten  minutes.  In 
order  to  obtain  the  neutral  sulphate,  dissolve  the  recrystal- 
lized  salt  (as  sold  by  the  dealers)  in  water,  add  a  small 
quantity  of  copper  oxide,  boil  until  the  copper  sulphate 
begins  to  crystallize,  filter  out  the  excess  of  oxide,  and 
concentrate  the  solution  until  it  is  completely  crystallized. 
Dry  the  crystals  by  draining  off  the  water,  should 
there  be  any,  and  pressing  them  between  layers  of  bibu- 
lous paper,  and  dissolve  them  in  water  in  the  proportion 
stated  above.  After  heating  the  solution  of  copper  sul- 
phate, containing  the  iron,  about  ten  minutes,  by  which 
means  the  iron  will  be  dissolved  and  copper  precipitated, 
add  20  c.  c.  of  a  solution  of  copper  chloride  (containing  1 
part  of  the  salt  in  2  parts  of  water),  and  50  c.  c.  of  con- 
centrated hydrochloric  acid,  and  heat  to  a  point  just  be- 
low boiling,  with  frequent  stirring,  until  the  precipitated 
copper  is  dissolved,  leaving  the  carbon  free.  Filter  it  out 
through  a  funnel,  made  of  large  glass  tubing.  The  funnel 
should  be  about  half  an  inch  in  diameter,  and  5  inches 
long,  and  drawn  at  one  end,  tG  a  point  about  4  mm.  wide. 
Fill  the  point  of  the  funnel  with  broken  glass,  up  to  the 
shoulder,  and  place  upon  the  glass  a  thin  layer  of  ignited 
asbestos,  pressing  it  carefully  against  the  walls  of  the 
funnel.  Care  should  be  taken  not  to  make  the  plug  of 
asbestos  too  thick  or  compact,  as  it  is  liable  to  become 
clogged  by  the  carbon.  The  layer  of  asbestos  should  be  thin 
enough  to  allow  water  to  run  through  at  the  rate  of  a  f un- 
nelful  in  ten  seconds.  Transfer  the  carbon  to  the  filter, 
and  wash  with  hot  water  until  it  is  free  from  chlorides. 
After  washing  down  all  the  carbon  from  the  sides  of  the 


TOTAL   CARBON.  107 

tube,  cut  it  off  about  1  inch  above  the  layer  of  carbon,  by 
scratching  the  glass  with  a  file,  and  pressing  a  red-hot 
glass  rod  against  the  cut.  Then  invert  the  part  contain- 
ing the  carbon  into  the  mouth  of  the  decomposing  flask 
of  an  apparatus  similar  to  that  described  in  the  analysis  of 
calcite,  for  the  determination  of  carbonic  acid  by  direct 
weight,  and  blow  the  contents  into  the  flask,  avoiding  the 
use  of  water  by  wiping  out  any  carbon  that  may  adhere 
to  the  glass  with  a  little  ignited  asbestos,  and  throwing 
this  also  into  the  flask.  To  the  filtrate  from  the  carbon 
add  4  or  5  c.  c.  of  concentrated  hydrochloric  acid  (to  pre- 
vent the  formation  of  any  precipitate  of  basic  copper  salt), 
and  dilute  with  water,  until  the  fluid  is  transparent.  If 
any  carbon  has  passed  through  the  asbestos  it  can  readily 
be  seen  in  the  transparent  fluid.  Should  there  be  any, 
allow  it  to  settle,  filter  it  out  on  another  filter  of  ignited 
asbestos,  and  add  it  to  that  in  the  flask.  Then  weigh  the 
absorption-tube,  introduce  into  the  flask  about  3  gms.  of 
chromic  acid,  put  the  apparatus  together,  and  start  the 
aspirator  very  slowly.  After  the  aspirator  has  run  long 
enough  to  partially  exhaust  the  air  in  the  apparatus,  intro- 
duce, through  the  funnel-tube,  about  30  c.  c.  of  pure  con- 
centrated sulphuric  acid,  close  the  stop-cock  of  the  funnel- 
tube,  and  heat  slowly  up  to  boiling.  After  the  acid  boils, 
remove  the  heat,  put  on  the  guard  tube,  open  the  stop- 
cock of  the  funnel-tube,  and  aspirate  slowly,  until  the  ab- 
sorption-tube is  cool.  After  it  is  thoroughly  cooled,  weigh 
it,  and  from  the  increase  of  weight,  due  to  carbonic  acid, 
calculate  the  carbon,  (For  Elliott' s  description,  consult  A. 
Yacher's  5th  Edition  of  Fres.  Quant,  Anal.,  London, 
1870.)     (See  cut  on  p.  25.) 

Professor  Langley  proposes  to  burn  the  carbon  directly 
in  a  current  of  oxygen,  after  treating  the  iron  with  copper 
sulphate.  His  directions  are  to  introduce  the  iron  or  steel 
in  a  finely-divided  condition  into  the  cold  solution  of 
copper  sulphate,  and  raise  the  heat  gradually,  on  a  water- 
bath,   to  80°  C,  with  frequent    stirring,  and   filter   tbe 


108  CAST-IROTT,    STEEL,    ETC. 

spongy  mass  on  a  common  funnel,  loosely  plugged  with 
asbestos.  A  porcelain  tube  of  about  three  fourths  of  an 
inch  internal  diameter  is  placed  in  a  furnace,  which  will 
keep  at  least  10  inches  of  the  tube  up  to  a  full  yellow  heat ; 
a  plug  2  inches  in  length  is  inserted  in  the  anterior  end. 
This  plug  is  made  by  coiling  up  fine  copper  bell- wire  till 
it  is  just  large  enough  to  fill  the  tube  closely  ;  the  inter- 
stices between  the  wires  will  always  be  large  enough  to 
allow  of  the  passage  of  gas.  Air  being  now  drawn  through 
the  apparatus,  the  copper  is  deeply  oxidized,  and  thus  a 
filter  of  oxide  of  copper  is  produced,  which,  at  a  red  heat, 
will  oxidize  any  carbonic  oxide  or  hydrocarbon  which  may 
pass  over  it.  To  hold  the  matter  to  be  burned,  a  copper 
boat  is  provided,  which  is  easily  made  by  folding  up  a 
piece  of  sheet  copper  ;  it  should  be  about  5  inches  long, 
and,  when  bent,  form  a  half  cylinder  with  closed  ends  ;  a 
few  small  holes  may  be  made  through  the  bottom  with  a 
punch,  in  order  to  make  the  vessel  porous.  On  the 
bottom  of  the  boat  a  stratum  of  asbestos  is  laid,  and  on 
this  the  mixed  copper  and  carbon  sponge  is  loosely  placed. 
The  anterior  end  of  the  tub§  containing  the  wire  plug  be- 
ing first  heated,  the  boat  is  then  introduced,  and  the  com- 
bustion conducted  in  the  usual  manner,  either  in  purified 
oxygen  or  air.  (See  Am.  Whem.,  Vol.  VI.,  September, 
1875.) 

Dr.  Eggertz,  of  the  Swedish  School  of  Mines,  has  pro- 
posed a  method  of  determining  the  combined  carbon  in 
iron  and  steel,  by  comparing  the  color  of  a  solution  of  the 
iron  or  steel  under  examination  with  that  of  a  solution  of 
another  sample  of  known  constitution.  When  steel  or 
pig-iron,  containing  carbon  in  chemical  combination,  is 
dissolved  in  nitric  acid,  a  soluble  brown  coloring  matter  is 
formed,  whose  coloring  power  is  very  intense,  and  the 
solution  assumes  a  tint  which  is  dark  in  proportion  to  the 
quantity  of  the  chemically  combined  carbon.  Iron  and 
graphite  do  not  influence  this  coloration,  for  the  solution 
of  ferrous  nitrate  is  colorless,  or,  at  most,  slightly  green- 


COMBINED   CARBON — COLORIMETRIC.  109 

ish,  unless  extremely  concentrated,  and  graphite  is  insol. 
uble  in  nitric  acid.  Thus,  in  dissolving  two  pieces  of  dif- 
ferent steels,  of  the  same  weight,  in  nitric  acid,  taking  care 
to  dilute  the  dark  solution  until  the  two  liquids  present 
exactly  the  same  color,  it  is  very  evident  that  the  more 
highly  carburetted  steel  will  furnish  the  larger  quantity  of 
liquid,  and  that  the  proportion  of  the  volumes  will  indi- 
cate the  relative  proportion  of  color  in  the  two  steels.  If, 
now,  the  composition  and  per  cent  of  carbon  of  one  of  the 
steels  is  known,  the  absolute  percentage  of  carbon  in  the 
other  steel  may  be  immediately  deduced.  Dr.  Eggertz 
has  applied  these  reactions  to  a  method  of  estimating  the 
combined  carbon.  In  a  cylindrical  test-tube,  dissolve 
gradually  in  the  cold  10  centigrammes  of  wrought-iron, 
steel,  or  cast-iron,  reduced  to  a  fine  powder,  in  1  J-  to  5  c.  c. 
of  nitric  acid  of  1.2  sp.  gr.  The  nitric  must  contain  no 
hydrochloric  acid,  because  the  solution  of  iron  would  have 
a  yellow  tint.  In  proportion  as  the  metal  contains  more 
carbon,  more  nitric  acid  must  be  used.  After  some  time, 
when  the  chief  part  of  the  metal  appears  to  be  attacked, 
place  the  tube  in  a  water-bath,  and  warm  it  to  80°  C,  in 
such  a  position  that  only  the  lower  part  of  the  tube  is  in 
contact  with  warm  water ;  a  movement  takes  place  in  the 
acid  which  favors  its  reaction  upon  the  metal ;  a  slight  dis- 
engagement of  gas  from  all  the  particles  of  carbon  may  be 
observed.  The  operation  should  always  be  conducted 
under  the  same  conditions  as  to  heat  and  length  of 
time.  The  evolution  of  gas  having  ceased  (in  operating 
upon  steel,  the  reaction  must  continue  two  or  three  hours), 
place  the  tubes  in  a  large  vessel  filled  with  cold  water,  to 
bring  the  solution  always  to  the  same  temperature.  This 
precaution  is  indispensable,  because  the  same  liquid  is 
darker  when  warm  than  when  cold.  Afterward,  pour  off, 
as  exactly  as  possible,  the  clear  liquid  into  a  graduated 
burette.  Upon  the  black  residue  remaining  in  the  tube, 
pour  some  drops  of  nitric  acid,  and  heat  carefully  over  a 
lamp.     If  there  is  no  further  liberation  of  gas,  the  residue 


110 

consists  of  nothing  but  graphite  or  silica.  Cool  the  new 
solution,  and  add  it  to  that  which  is  already  in  the  bu- 
rette. The  liquid  is  then  diluted  with  water  until  its  color 
corresponds  exactly  with  that  of  the  normal  liquid,  which 
latter  should  be  of  such  a  degree  of  concentration  that 
each  c.  c.  represents  0.0001  gm.  of  carbon.  If,  for  instance, 
this  normal  liquid  is  prepared  from  cast-steel  containing 
exactly  0.85  per  cent  of  carbon,  1  decigramme  of  that  steel 
must  be  dissolved  in  8.5  c.  c.  of  nitric  acid;  iOO  gms.  of 
steel,  containing  85  centigrammes  of  carbon,  would  thus 
be  dissolved  in  8500  c.  c.  of  the  normal  solution  ;  100  c.  c. 
of  that  solution  would  represent  1  centigramme  of  carbon, 
and,  consequently,  1  c.  c.  of  the  normal  solution  would  rep- 
resent 0.0001  gm.  of  carbon. 

To  compare  the  normal  solution  with  the  solution  of  iron 
under  examination,  it  should  be  contained  in  a  tube  of  the 
same  kind,  and  when  the  two  tubes  are  held  together  by 
daylight  before  a  thin  sheet  of  paper,  the  color  should  be 
exactly  the  same  in  both  of  them.  As  the  normal  solution 
alters  slightly  in  color  by  keeping,  and  begins  to  become 
paler  after  24  hours,  it  is  not  possible  to  keep  such  a  solu- 
tion for  use  in  a  tube  hermetically  sealed.  A  solution  of 
burnt  sugar  in  weak  alcohol  gives  a  solution  of  exactly  the 
same  shade  of  color  as  the  normal  solution,  and  maintains 
its  color  for  a  considerable  time  when  protected  from  the 
light.  A  solution  of  roasted  coffee  in  alcohol  has  also  been 
found  to  be  very  satisfactory,  But  the  best  plan  is  to 
make  the  solution  fresh,  as  it  is  required,  by  dissolving  0.1 
gm.  of  steel,  containing  a  known  amount  of  carbon,  in  5 
c.  c.  of  nitric  acid,  and  diluting  it  to  the  requisite  degree, 
which  may  be  indicated  by  a  mark  upon  the  tube  corre- 
sponding to  the  percentage  of  carbon  in  the  steel.  If  an 
iron  solution  of  exactly  the  same  color  as  the  normal  solu- 
tion is  diluted  with  one  tenth  of  its  bulk  of  water,  the  color 
becomes  distinctly  paler,  so  that  the  delicacy  of  the  method 
may  be  judged  of  from  this. 

J.  Blodgett  Britton,  in  the  Jour,  of  tlie  Franklin  Insti- 


COMBINED   CARBON — COLORIMETEIC.  Ill 

tute  for  May,  1870.  lias  suggested  a  modification. 
Instead  of  a  single  tube,  containing  a  standard  solution  for 
comparison,  a  number  of  tubes,  having  their  solutions  dif- 
ferently standardized  one  from  the  other,  are  employed. 
They  are  arranged  securely  in  a  wooden  frame,  with  spaces 
between  for  placing  the  tube  containing  the  solution  to  be 
tested.  The  tubes  aTe  five  eighths  of  an  inch  in  diameter, 
and  three  and  a  half  inches  in  length,  filled  with  water  and 
alcohol,  colored  with  roasted  coffee,  and  hermetically 
sealed.  The  solution  in  the  first  tube  has  its  color  to  cor- 
respond exactly  with  one  produced  by  1  gm.  of  iron  con- 
taining 0.02  per  cent  of  combined  carbon,  dissolved  in  15 
c.  c.  of  nitric  acid.  The  solution  in  the  tube  next  to  it  has 
its  color  to  correspond  with  one  produced  by  the  same 
quantity  of  iron,  but  containing  0.04  per  cent  of  combined 
carbon,  and  so  with  each  of  the  other  tubes,  increasing 
0.02  per  cent  of  carbon  in  regular  succession,  the  last 
reaching  0.3  per  cent,  which  is  indicated  by  figures  on 
the  rail  of  the  frame  opposite  each  tube.  On  the  back  of 
the  instrument  is  stretched  some  fine  white  parchment 
paper. 

The  process  is  conducted  as  follows  : 

One  gm.  of  the  finely-divided  metal  is  put  into  a  tube  of 
about  1.5  inches  in  diameter  and  10  inches  long,  and  di- 
gested for  15  or  20  minutes  in  10  c.  c.  of  nitric  acid  of  a 
little  more  than  1.2  sp.  gr.,  free  from  chlorine.  The  solu- 
tion is  then  cautiously  poured  into  a  beaker,  and  a  small 
portion  of  metal,  which  remains  undissolved  and  adheres 
to  the  bottom  of  the  tube,  is  treated  with  5  c.  c.  of  fresh 
acid,  exposed  to  a  gentle  heat  till  completely  dissolved, 
and  added  to  the  other.  The  contents  of  the  beaker,  when 
sufficiently  cool,  are  filtered  through  two  thicknesses  of 
German  paper  (not  previously  moistened,  and  of  a  diam- 
meter  not  exceeding  4.5  inches)  into  a  tube  about  five 
inches  long,  and  of  precisely  the  same  diameter  as  those 
in  the  instrument.  After  the  filtered  solution  has  re- 
mained for  some  minutes  at  the  temperature  of  the  atmo- 


112 

sphere,  and  its  color  become  fixed,  the  tube  is  placed  in 
the  instrument,  and  the  carbon  determined  by  a  compari- 
son of  shades  ;  the  determination  may  be  made  readily  as 
closely  as  0.01  per  cent.  Heat  should  not  be  applied  in 
the  first  instance  to  facilitate  the  solution  of  the  metal,  be- 
cause a  high  temperature  is  apt  to  cause  a  slight  change 
of  color.  Two  thicknesses  of  paf)er  are  taken  be- 
cause one  is  liable  to  break,  and  the  paper  should  be 
used  dry,  for,  if  previously  wetted,  the  water  will  weaken 
the  color  of  the  solution,  and  it  ought  to  be  cut  to  a  size 
not  exceeding  4.5  inches,  to  prevent  undue  absorption. 

If  the  metal  to  be  examined  contains  more  than  0.3  per 
cent  of  carbon,  0.5  gm.,  or  less,  of  it  may  be  taken,  or  the 
solution  may  be  diluted  with  an  equal  volume  of  water,  or 
more,  and  the  proper  allowance  made  ;  or  an  instrument 
of  higher  range  may  be  used.  On  the  other  hand,  if  the 
metal  contains  a  very  small  percentage  of  carbon,  2  gms. 
of  it  may  be  taken.  (Compare  Crookes'  s  Select  Methods, 
p.  81.) 

For  other  methods,  consult  Fres.,  Quant.  Anal.,  4th 
London  Ed.,  §249. 

For  the  determination  of  the  graphite  Eggertz's  method 
is  as  follows  :  One  gramme  or  more  of  iron,  reduced  to 
small  pieces,  or  white  pig-iron  crushed  in  a  steel  mortar, 
or  gray  pig-iron  in  small  chips,  is  dissolved  in  15  c.  c.  of 
hydrochloric  acid  of  1.12  density,  in  a  small  flask  covered 
with  a  watch-glass,  and,  when  the  iron  is  dissolved,  the  so- 
lution boiled  for  half  an  hour.  All  the  carbon  combined 
with  the  iron  is  disengaged  in  the  form  of  carburetted  hy- 
drogen gas,  while  the  graphite  and  silica  remain.  If  the 
carbonaceous  residue,  left  after  dissolving  the  iron,  comes 
in  contact  with  atmospheric  air  before  the  liquid  is  boiled, 
it  is  so  altered  that  it  is  not  dissolved,  and  disengaged  as 
gas.  The  graphite  that  remains  after  boiling  the  liquid  is 
collected  on  a  filter  of  known  weight,  washed,  dried,  and 
weighed.  It  is  then  burnt,  and  the  residual  silica  weighed 
to  ascertain  the  weight  of  graphite.      See  Crookes' s  Select 


GRAPHITIC    CARBON.  113 

Methods,  pp.  79  and  80,  where  a  modification  is  proposed, 
as  follows : 

In  a  beaker  of  100  c.  c.  capacity,  mix  4  c.  c.  of  sulphuric 
acid  and  20  c.  c.  of  water,  and  when  the  heat  produced  by 
the  combination  of  the  water  and  the  acid  has  entirely 
disappeared,  shake  2  gms.  of  finely  powdered  pig-iron 
into  the  dilute  acid,  and  boil  for  half  an  hour.  (For  steel 
and  wrought-iron  not  less  than  3  gms.  should  be  taken, 
and  the  acid  for  solution  increased  in  proportion. )  The 
solution  is  then  evaporated  until  it  measures  18  c.  c, 
allowed  to  cool  to  the  temperature  of  50°  C,  and  4  c.  c.  of 
nitric  acid  of  sp.  gr.  1.20  added  ;  boil  for  a  quarter  of  an 
hour,  and  allow  to  evaporate  on  a  water-bath  until,  on 
holding  a  watch-glass  over  the  beaker,  there  occurs  upon 
it  no  perceptible  condensation.  To  the  dry  mass  add  30 
c.  c.  of  water,  and  5  c.  c.  of  hydrochloric  acid,  sp.  gr. 
1.16,  boil  for  a  quarter  of  an  hour,  and  add  more  hydro- 
chloric acid  if  there  appears  to  be  anything  besides  silica 
and  graphite  undissolved.  The  insoluble  silica  and 
graphite  are  thrown  on  a  filter  (which  has  been  dried  at 
100°  C.  and  carefully  weighed),  washed  with  cold  water 
until  the  washings  give  no  reaction  for  iron  when  tested 
with  potassium  ferrocyanide,  then  washed  with  boiling 
water  containing  5  per  cent  of  nitric  acid.  The  silica  and 
graphite  are  then  dried  on  the  filter  at  100°  C,  and 
weighed,  ignited  in  a  porcelain  crucible,  and  the  weight 
carefully  taken.  The  difference  between  the  weighings 
before  and  after  ignition  gives  the  amount  of  the 
graphite. 

The  objection  to  the  method  of  determining  the  graphite 
by  burning  it,  after  drying  it  at  100°  C,  when  mixed  with 
silica,  is  that  at  that  temperature  water  is  not  expelled 
from  the  silica,  or  even  at  a  much  higher  heat.  Conse- 
quently, the  loss  which  represents  the  weight  of  graphite  is 
partly  water.  This  objection  applies  to  all  methods  where 
the  graphite  is  determined  by  igniting  and  weighing  the 
residual  silica.     The  extreme  difficulty,  at  times,  of  burning 


114 

the  graphite  in  a  crucible  may  be  considered  another 
objection. 

The  best  method  is  to  dissolve  from  2  to  3  gms.  of  gray 
pig-iron,  or  from  4  to  5  gms.  of  white  iron,  steel,  or 
wronght-iron  in  dilnte  hydrochloric  acid,  and  boil  for 
about  half  an  hour,  filter  through  asbestos  in  a  funnel 
made  of  glass  tubing,  and  arranged  as  directed  for  the 
determination  of  total  carbon ;  wash  with  hot  water  until 
all  acid  is  washed  out,  then  with  strong  solution  of  potas- 
sium hydrate,  which  will  remove  silica,  afterward  with 
hot  water,  to  wash  out  any  potassium  carbonate,  of  which 
the  potassium  hydrate  is  apt  to  contain  some,  then  with 
alcohol  (which  will  remove  hydrocarbons)  until  the 
alcohol  runs  through  the  funnel  colorless,  again  with  a 
little  hot  water,  then  with  ether  until  it  passes  through 
colorless,  in  order  to  displace  the  water,  and  remove 
another  class  of  hydrocarbons,  which  the  alcohol  may  have 
failed  to  reach.  It  is  well,  finally,  to  wash  with  a  little 
hot  water  (particularly  if  the  ether  used  is  not  perfectly 
pure),  in  order  to  keep  the  graphite  from  adhering  to  the 
walls  of  the  funnel,  when  blown  into  the  decomposing- 
flask,  being  careful  to  remove  any  excess  of  water  by 
gently  blowing  through  the  funnel.  After  the  graphite  is 
thoroughly  washed,  it  is  transferred  to  the  decomposing- 
flask,  and  oxidized  with  chromic  and  sulphuric  acids,  in 
precisely  the  same  manner  as  in  the  determination  of  total 
carbon.  If  it  is  preferred,  the  graphite  may  be  transferred 
to  a  boat,  and  burned  in  a  current  of  oxygen  as  in 
"  Sugar  (Ultimate  Analysis)." 

To  determine  the  silicon,  sulphur,  and  phosphorus,  dis- 
solve 10  gms.  of  potassium  chlorate  in  200  c.  c.  of  hot 
water,  in  a  flask  holding  at  least  1  litre,  heat  to  boiling, 
and  introduce  5  gms.  of  the  iron,  in  the  form  of  borings 
or  chips.  Then  remove  the  source  of  heat,  add  (little  by 
little)  60  c.  c.  of  pure  concentrated  hydrochloric  acid,  and 
heat  until  the  iron  is  dissolved,  which  may  be  known  by 
there  being  no  heavy  particles  on  the  bottom  of  the  flask. 


PHOSPHORUS — SILICON.  115 

which  will  not  rise  when  the  flask  is  shaken.  There  may 
be  a  large  quantity  of  black  carbon  in  the  fluid,  but  this 
will  rise  when  agitated.  Transfer  the  contents  of  the  flask 
to  a  large  casserole,  evaporate  to  dryness  on  a  water-bath, 
and  then  heat  in  an  air-bath,  at  about  110°  C,  until  the 
odor  of  hydrochloric  acid  cannot  be  detected.  To  the 
thoroughly  dry  mass  add  10  c.  c.  of  hydrochloric  acid, 
and  30  c.  c.  of  water,  and  heat  on  a  water-bath  until 
everything  is  dissolved  except  silica  and  graphite.  Then 
dilute  with  50  or  60  c.  c.  of  water,  filter,  and  wash  with 
cold  water,  until  the  washings  give  no  reaction  for 
chlorine.  To  the  filtrate  add  ammonia  in  excess,  to  pre- 
cipitate the  ferric  hydrate,  which  will  carry  the  phos- 
phorus with  it,  and  wash  until  the  washings  give  no  reac- 
tion for  sulphuric  acid.  Acidulate  the  filtrate  slightly 
with  hydrochloric  acid,  precipitate  barium  sulphate  as 
usual,  and  calculate  the  sulphur.  In  almost  all  cases,  2 
c.  c.  of  a  saturated  solution  of  barium  chloride  will  be  suf- 
ficient to  precipitate  all  the  sulphur  in  5  gms.  of  iron.  It 
is  well,  however,  to  be  assured  that  a  sufficient  quantity 
of  the  reagent  has  been  added,  by  testing  a  few  drops  of 
the  filtrate  with  sulphuric  acid,  as  directed  in  the  analysis 
of  magnesium  sulphate. 

To  determine  the  phosphorus,  dissolve  the  precipitate  of 
ferric  hydrate,  containing  ferric  phosphate,  in  hydro- 
chloric acid,  and  proceed  as  directed  in  partial  analysis  of 
iron  ore  by  Method  No.  2. 

To  determine  the  silicon,  dry  the  residue  (containing 
silica,  graphite,  and  perhaps  a  little  ferric  oxide)  left  after 
filtering  the  solution  of  5  gms.  of  iron,  burn  it  in  a  plat- 
inum crucible,  add  5  or  6  gms.  of  sodium  carbonate,  and 
2  or  3  gms.  of  sodium  nitrate,  and  heat  over  a  good  burner 
until  the  contents  of  the  crucible  are  fluid  and  the  graphite 
oxidized.  Do  not  heat  unnecessarily.  Treat  the  fused 
mass  as  directed  in  the  analysis  of  feldspar  for  the  determi- 
nation of  silica.  As  the  silica  obtained  may  contain  a 
little  ferric  oxide  and  platinum  from  the  crucible,  expel  it 


116  CAST-IKON,    STEEL,    ETC. 

by  means  of  hydrofluoric  and  sulphuric  acids,  and  from 
the  loss  calculate  the  silicon.  The  estimation  of  the  silicon 
by  treating  the  original  residue  with  hydrofluoric  and 
sulphuric  acids,  before  removing  the  graphite,  would  be 
erroneous,  as  some  of  the  graphite  would  also  be  expelled 
by  the  action  of  the  acids.  Such  has  been  the  experience 
of  the  writer. 

A  common  method  of  determining  sulphur  in  iron  is  to 
dissolve  a  weighed  quantity  of  the  iron  with  hydrochloric 
acid  in  a  flask  or  retort,  conducting  the  sulphuretted 
hydrogen  formed  into  a  solution  containing  some  metal, 
which  will  be  precipitated  as  sulphide,  oxidizing  the  sul- 
phur of  the  sulphide  into  sulphuric  acid,  and  precipitating 
it  with  barium  chloride.  Dr.  Drown  has  substituted  a 
solution  of  potassium  permanganate.  By  his  method,  5 
or  6  gms.  of  the  iron  are  dissolved  in  hydrochloric  acid, 
and  the  sulphuretted  hydrogen  resulting  conducted  into  a 
solution  of  1  gm.  of  potassium  permanganate  in  200  c.  c. 
of  water,  contained  in  three  tubes  or  bottles.  After  the 
evolution  of  the  gas  has  entirely  ceased,  and  air  has  been 
drawn  through  the  tubes  or  bottles  for  some  time,  the 
contents  are  poured  into  a  beaker,  and  the  bottles  rinsed 
out  with  water,  and  any  manganese  oxide  dissolved  in  a 
little  hydrochloric  acid.  Enough  hydrochloric  acid  is  then 
added  to  the  beaker  to  completely  decompose  the  per- 
manganate and  convert  it  into  a  clear,  colorless  solution, 
in  which  the  sulphuric  acid  may  be  directly  precipitated. 
If  the  solution  does  not  become  perfectly  clear,  owing  to 
impurities  in  the  permanganate  used,  filtration  is  necessary 
before  precipitation.  Before  precipitating  the  sulphuric 
acid,  the  residue  left  after  treatment  with  hydrochloric 
acid  in  the  flask  is  filtered  off  and  washed,  then  evaporated 
twice  to  dryness  with  aqua  regia,  taken  up  with  hydro- 
chloric acid,  filtered,  and  the  filtrate  added  to  the  main 
solution.     (See  Am.  Chemist,  Yol.  IV.,  May,  1874.) 

For  a  colorimetric  method  of  estimating  sulphur  in  iron 
by  Eggertz,  see  Crookes'  s  Select  Methods,  p.  85. 


CHROMIUM,    ALUMINUM,    ETC.  117 

For  the  determination  of  chromium,  aluminum,  manga- 
nese, zinc,  nickel,  cobalt,  calcium,  and  magnesium,  dis- 
solve 5  gms.  of  iron  or  steel,  in  the  same  manner  as  for  the 
determination  of  silicon,  sulphur,  and  phosphorus,  with 
hydrochloric  acid  and  potassium  chlorate,  and  after 
evaporating,  drying,  dissolving  the  mass,  and  filtering 
out  the  silica  (which  may  be  determined  here,  as  a  check 
on  the  previous  determination),  proceed  as  directed  in 
Notes  3  and  4  of  "  Complete  Analysis  of  Iron  Ore  "  for  the 
determination  of  chromium,  and  the  treatment  of  residues 
and  precipitates. 

Dissolve  the  precipitate  caused  by  sodium  carbonate,  in 
the  treatment  for  chromium,  in  hydrochloric  acid,  add  to 
it  the  solution  of  any  residue,  and  precipitate,  as  directed 
in  Note  4  of  "  Complete  Analysis  of  Iron  Ore, ' '  and  boil  with 
the  addition  of  2  or  3  c.  c.  of  nitric  acid,  to  ensure  com- 
plete oxidation  of  iron.  Then  precipitate  basic  acetates 
twice,  as  directed  in  the  analysis  of  manganese  ore,  filter, 
and  wash  well. 

In  the  filtrate  from  the  basic  acetates  will  be  found  the 
manganese,  zinc,  nickel,  cobalt,  calcium,  and  magnesium. 
For  their  separation  and  determination,  consult  Note  16  of 
"  Complete  Analysis  of  Iron  Ore." 

If  no  zinc,  nickel,  or  cobalt  be  present,  the  manganese 
may  be  precipitated  by  bromine,  and  determined  immedi- 
ately, as  directed  in  Note  12  of  "  Complete  Analysis  of  Iron 
Ore,"  and  the  calcium  and  magnesium  determined  in  the 
filtrate  from  the  manganese  as  in  Notes  13  and  14. 

To  determine  the  aluminum,  dry  the  precipitated  ace- 
tates, transfer  them  to  a  silver  crucible,  burn  the  filter,  add 
the  ash,  and  fuse  with  pure  sodium  or  potassium  hydrate ; 
then  boil  the  fused  mass  with  water.  By  this  means,  the 
alumina  will  be  dissolved.  Filter,  wash,  acidify  the 
alkaline  filtrate  strongly  with  hydrochloric  acid,  add 
slight  excess  of  ammonia,  and  determine  the  alumina  as 
in  the  analysis  of  potash  alum,  from  which  calculate  the 
aluminum.     H.  Eose,  who  suggested  the  fusion  with  po- 


118  CAST-IRON,    STEEL,    ETC. 

tassium  hydrate,  precipitates  the  alumina  with  ammonium 
carbonate,  from  the  solution,  strongly  acidified  with 
hydrochloric  acid.  (See  his  Quant.  Anal.,  "  Separation  of 
Alumina  from  Ferric  Oxide.") 

To  determine  copper,  tin,  arsenic,  and  antimony,  treat 
20  gms.  of  the  iron  in  the  finest  possible  state  of  division 
with  a  previously-heated  mixture  of  1  volume  of  nitric 
acid  and  3  volumes  of  hydrochloric  acid  (both  acids  must 
be  pure  and  strong)  in  a  very  capacious,  long-necked, 
obliquely  placed  flask,  at  a  gentle  heat.  When  all  visible 
action  has  ceased,  decant  the  solution,  and  treat  the 
residue  with  a  fresh  portion  of  aqua  regia.  Mix  the  solu- 
tions, dilute  copiously,  and  treat  in  a  large  flask  with 
sulphuretted  hydrogen,  at  first  in  the  cold,  then  at  70°  C. 
Allow  the  fluid  (saturated  with  sulphuretted  hydrogen)  to 
settle  for  24  hours,  filter,  dry  the  precipitate,  which  con- 
sists principally  of  sulphur,  and  extract  it  with  bisulphide 
of  carbon.  There  usually  remains  a  small  black  residue, 
which  often  contains,  besides  sulphide  of  copper,  a  little 
sulphide  of  arsenic  and  sulphide  of  antimony.  (See  Fres., 
Quant.  Anal.,  §  249-5.)  There  may  be  also  sulphides 
of  other  metals  of  Groups  V.  and  VI.  Filter  out  the 
precipitated  sulphides,  wash  and  digest  the  precipitate 
with  potassium  hydrate  and  potassium  sulphide  contain- 
ing an  excess  of  sulphur.  The  copper  sulphide  will 
remain  undissolved  while  the  sulphides  of  tin,  antimony, 
and  arsenic  will  go  into  solution.  Decompose  the  copper 
sulphide  with  nitric  acid,  replace  the  nitric  with  sulphuric 
acid,  and  determine  the  copper  electrolyticaily,  as  in  the 
analysis  of  copper  ore. 

For  the  determination  of  the  tin,  arsenic,  and  antimony, 
consult  analysis  of  type  metal. 

To  determine  the  alkaline  metals,  dissolve  20  gms.  of  the 
iron  in  dilute  hydrochloric  acid,  evaporate  nearly  to  dryness, 
on  a  water -bath,  in  order  to  remove  large  excess  of  free  acid, 
add  water,  and  boil.  Add  to  the  solution  an  excess  of 
barium  hydrate,  and  proceed  as  in  the  analysis  of  feldspar. 


NITROGEN.  US 

To  determine  the  nitrogen,  treat  about  2  gms.  of  the 
finely-divided  cast-iron,  in  a  tubulated  retort,  with  a  solu- 
tion of  10  gms.  of  neutral  crystallized  copper  sulphate, 
and  6  gms.  of  fused  sodium  chloride.  When  the  iron  is 
dissolved,  add  milk  of  lime,  and  distill,  until  half  the  fluid 
has  passed  over  into  a  receiver  which  -contains  a  sufficient 
amount  of  standard  solution  of  sulphuric  acid,  and  deter- 
mine the  amount  of  sulphuric  acid  neutralized  by  the  am- 
monia, which  has  been  expelled,  by  titration  with  standard 
solution  of  potash,  as  in  the  analysis  of  guano  (which 
consult;  also  see  Fres.,  Quant.  Anal.,  §249,  4th  London 
Edition).  For  a  description  of  the  apparatus,  and  the 
method  of  making  the  distillation,  consult  Fres.,  Quant. 
Anal.,  §  99 — 3 — a.,  p,  157.  The, ammonia  is  calculated  to 
nitrogen.  Thorpe  suggests  that  the  nitrogen,  if  minute  in 
quantity,  may  be  determined  by  Nessler'  s  solution.  (See 
analysis  of  potable  water.)  Only  a  part  of  the  nitrogen  is 
evolved  by  this  treatment ;  the  rest  remains  in  the  car- 
bonaceous residue.  Ullgren  determines  this  by  combus- 
tion with  mercuric  sulphate,  and  measurement  of  the 
evolved  nitrogen.  The  apparatus  consists  of  an  ordinary 
combustion-tube,  about  30  c.  c.  long,  one  end  of  which  is 
closed  by  fusion.  It  is  then  filled  for  about  5  c.  c.  with 
magnesite  or  sodium  bicarbonate,  on  which  is  placed  a 
plug  of  asbestos.  A  mixture  of  about  0.1  gm.  of  the  car- 
bonaceous residue  (previously  dried  at  130°  C),  and  3.5  or 
4  gms.  of  mercuric  sulphate,  is  then  made  in  an  agate 
mortar,  and  transferred  to  the  tube,  together  with  a  small 
quantity  of  mercuric  sulphate,  used  to  rinse  the  mortar. 
An  asbestos  plug  follows  next ;  then,  for  about  one  third 
of  the  remainder  of  the  tube,  a  layer  of  pumice,  mixed 
with  moistened  mercuric  sulphate  and  dried ;  on  this  is 
placed  a  plug  of  asbestos.  Finally,  the  tube  is  filled  with 
pumice,  which  has  been  boiled  in  a  concentrated  solution 
of  potassium  bichromate,  and  allowed  to  drain.  This  serves 
to  absorb  the  sulphur  dioxide  which  may  be  formed.  The 
tube  is  then  closed  with  a  caoutchouc  stopper,  through 


120 

which  passes  a  small  tube,  so  bent  that  it  passes  down 
into  a  mercury  trough,  and  up  under  a  vertical  tube  hold- 
ing about  90  c.  c,  having  a  bulb  of  a  capacity  of  about 
40  c.  c.  blown  in  it,  in  such  a  way  that  the  part  above  the 
bulb  will  hold  about  20  c.  c,  and  the  part  below  the  bulb 
about  30  c.  c.  The  narrower  part  is  graduated  to  divis- 
ions of  0.1  c.  c.  The  tube  is  filled  with  mercury,  and  in- 
verted in  the  bath.  Solution  of  potassium  hydrate  (1  part 
potassium  hydrate  and  2  parts  water)  is  introduced  until 
the  bulb  is  filled  to  within  about  10  c.  c,  and  then  15  c.  c. 
of  a  saturated  and  clear  solution  of  tannic  acid.  The  ex- 
treme end  of  the  tube,  where  the  magnesite  is  placed,  is 
now  heated  gently,,  the  heat  being  gradually  extended 
and  increased  until  about  half  the  carbonate  is  decom- 
posed, thus  expelling  the  air.  The  turned-up  end  of  the 
delivery-tube  is  then  brought  under  the  graduated-tube, 
and  'the  part  of  the  combustion-tube  containing  the  car- 
bonaceous residue  heated  gently.  Then  the  part  containing 
the  pumice  and  mercuric  sulphate  is  heated,  and  when  it 
is  red  hot,  that  containing  the  residue  is  heated  to  strong 
red  heat.  When  gas  ceases  to  be  evolved,  heat  the  rest  of 
the  carbonate  to  sweep  the  tube.  Transfer  the  receiving- 
tube  to  a  water-trough,  when  the  mercury  and  potash  will 
be  replaced  by  water.  Measure  the  nitrogen,  making  cor- 
rections for  temperature  and  pressure,  and  calculate  nitro- 
gen.    (Fres.,  Quant.  Anal.,  §  249,  4th  London  Edition.) 

To  determine  vanadium,  dissolve  40  or  50  gms.  of  the 
iron,  reduced  to  a  finely-divided  condition  by  filing  or 
drilling,  in  dilute  sulphuric  acid.  Filter  out  and  wash  the 
black  residue,  which  will  contain  all  but  traces  of  the 
vanadium,  and  proceed  as  directed  in  Appendix  3,  of 
" Complete  Analysis  of  Iron  Ore."  (Consult,  also,  H. 
Rose,  Quant.  Anal.,  p.  498.) 

To  determine  molybdenum,  treat  a  large  quantity  of  the 
iron,  as  for  vanadium,  with  dilute  sulphuric  acid.  Filter 
out  and  wash  the  residue,  digest  it  with  yellow  ammonium 
sulphide,  which  will  dissolve  the  molybdenum,  with  other 


MOLYBDENUM — SLAG.  121 

metals  whose  sulphides  are  soluble  in  the  alkaline  sul- 
phides. Filter,  wash,  and  acidulate  the  filtrate.  Tore-pre- 
cipitate the  sulphide,  filter,  wash,  digest  with  strong  nitric 
acid  to  oxidize  the  sulphur,  make  alkaline  with  ammonia, 
and  filter.  All  molybdic  acid  should  go  into  solution. 
Then  make  the  solution  sligMly  acid  with  nitric  acid, 
allow  it  to  stand  for  some  hours,  and  add  solution  of 
neutral  mercurous  nitrate  in  sufficient  quantity.  The 
yellow  precipitate,  which  is  at  first  bulky,  soon  contracts. 
Filter  on  a  weighed  filter,  wash  with  a  dilute  solution  of 
mercurous  nitrate,  dry,  transfer  the  dry  precipitate  as 
completely  as  possible  from  the  filter  to  a  platinum  or 
porcelain  crucible,  and  ignite  in  a  stream  of  hydrogen, 
cool,  and  weigh,  and  repeat  until  the  weight  remains  con- 
stant. The  heat  should  not  be  raised  above  gentle  redness. 
Finally,  weigh  the  dioxide,  and  calculate  the  molybdenum. 
As  molybdic  acid  is  volatile,  instead  of  burning  the  filter, 
weigh  it,  and  from  the  weight  of  the  small  portion  of  pre- 
cipitate adhering,  calculate  the  molybdenum,  and  add  the 
weight  to  the  other.  (See  H.  Rose,  Quant.  Anal.,  article 
" Molybdenum,"  p.  490.) 

To  determine  any  slag  that  may  be  mixed  with  cast-iron, 
pulverize  about  3  gms.  as  finely  as  possible  by  boring  with  a 
dull  drill  and  rubbing  in  a  steel  mortar,  being  careful  not 
to  lose  any  of  the  dust.  Add  this  (little  at  a  time)  to  6 
c.  c.  of  bromine,  previously  mixed  with  60  c.  c.  of  water 
which  has  been  boiled  and  cooled  to  0°  C.  in  a  beaker  of 
about  100  c.  c.  capacity.  Keep  the  fluid  at  0°  C.  for  3 
hours,  with  frequent  stirring.  No  evolution  of  gas  should 
take  place.  After  the  iron  appears  to  have  dissolved, 
allow  the  fluid  to  stand  for  24  hours  at  the  ordinary  tem- 
perature of  the  atmosphere.  Then  add  30  c.  c.  of  ice- 
water,  which  has  been  previously  boiled,  allow  the  mixture 
to  settle,  and  decant,  on  a  small  filter,  the  fluid  containing 
light  particles  of  carbon.  Repeat,  until  only  hard,  dark 
powder  remains  at  the  bottom  of  the  beaker.  Test  this  for 
mdissolved  iron,  by  adding  2  drops  of  hydrochloric  acid, 


122  CAST-IKON,    STEEL,    ETC. 

and  5  c.  r.  of  water.  If  any  iron  be  present,  gas  will  be 
evolved.  Whether  iron  be  present-  or  not,  decant  imme- 
diately on  the  filter,  and  wash,  to  avoid  affecting  the  slag. 
If  the  hydrochloric  acid  has  shown  the  presence  of  iron, 
add  30  c.  c.  of  ice-cold  water,  which  has  been  previously 
boiled,  and  3  c.  c.  of  bromine,  and  proceed  as  in  the  first 
instance,  in  order  to  dissolve  all  iron.  Filter,  and  wash 
with  cold  water,  until  the  washings  give  no  reaction  for 
iron.  Dry  the  filter  and  contents,  ignite,  transfer  the 
ignited  substance  to  a  silver  or  platinum  dish,  add  solution 
of  pure  sodium  hydrate,  and  digest,  to  dissolve  free 
silica.  Then  filter,  wash  well,  dry,  ignite,  cool,  and 
weigh  the  slag.  Iodine  may  be  used  instead  of  bromine. 
If  iodine  be  used,  add  the  same  quantity  of  iron,  reduced 
to  as  fine  a  powder  as  possible,  to  15  gms.  of  iodine,  cov- 
vered  with  15  c.  c.  of  water,  in  a  beaker  of  about  100  c.  c. 
capacity,  the  water  having  been  boiled  previously  to  re- 
move any  air  adhering  to  the  iodine,  and  cooled  by  stand- 
ing in  ice.  After  adding  the  iron,  proceed  as  when  bro- 
mine is  used. 

Consult  Fres.,  Zeits.fur  Anal.  Chem.,  1865,  pp.  69-77  ; 
Wag.,  Jdhresb.,  1863,  p.  19  ;  same,  1865,  p.  27  ;  same,  1868, 
p.  28 ;  Comp.  Bend.  2,  p.  1030 ;  Dingier,  clxxvii.,  p.  388 ; 
Eggertz,  Jahresb.,  1863,  p.  30. 


CHAPTER   XVIII. 


ZINC    ORE. 


Make  a  qualitative  examination  of  the  ore,  for  metals  oi 
Groups  Y.  and  VI. 

Treat  2  gms.  of  the  finely  pulverized  ore,  in  a  small 
flask,  with  a  mixturo  of  10  c.  c.  of  hydrochloric  acid,  5 
c.  c.  of  nitric  acid,  and «)  c.  c.  of  sulphuric  acid  ;  all  the 
acids  being  pure  and  concentrated.  Boil,  until  copious 
fumes  of  S03  are  evolved,  cool,  dilute  with  25  c.  c.  of 
water,  filter,  and  wash  well.  If  the  qualitative  analysis 
has  shown  the  presence  of  oxides  of  the  higher  groups, 
add  5  c.  c.  of  hydrochloric  acid,  and  saturate  the  solution, 
which  should  not  exceed  500  c.  c,  with  sulphuretted  hy- 
drogen. Filter,  wash  slightly,  digest  the  precipitate  with 
a  mixture  of  5  c.  c.  of  hydrochloric  acid,  and  10  c.  c.  of 
water,  over  heat,  dilute  to  about  400  c.  c,  and,  without 
filtering,  saturate  with  sulphuretted  hydrogen.  (See  Fres., 
Quant.  Anal.,  §162 — A,  p.  375.)  Filter,  wash  well  with 
hot  water,  combine  the  filtrates,  and  boil,  after  adding  a 
little  potassium  chlorate  to  oxidize  the  sulphur,  and  pre- 
cipitate basic  acetates  as  usual.  If  no  metals  of  the  higher 
groups  be  present,  the  treatment  with  sulphuretted  hy- 
drogen and  potassium  chlorate  is  to  be  omitted.  In 
either  case,  filter  out  the  precipitate  of  basic  acetates,  dis- 
solve it  in  hydrochloric  acid,  dilute,  and  precipitate  again 
in  the  same  way.  Filter,  dissolve  the  precipitate  as  before, 
and  precipitate,  a  third  time,  with  large  excess  of  ammonia, 
filter,  and  wash.  Combine  all  the  filtrates,  concentrate 
them  to  500  c.  c,  acidify  strongly  with  acetic  acid,  boil, 
and,  while  boiling,  pass  a  rapid  current  of  sulphuretted  hy- 
drogen for  half  an  hour.  By  this  means,  the  zinc  will  be 
precipitated  as  sulphide,  and  the  manganese  be  held  in  so- 
lution.     (See   Fres.,    Quant.    Anal.,   §  160 — 6 — a ;    also 


124  ZINC   OKE. 

Gibbs,  in  Am.  Jour.  Sci.  and  Arts,  January  7,  1868.)  If 
there  be  a  very  large  amount  of  manganese  in  the  ore,  it  is 
well  to  dissolve  the  zinc  sulphide  in  hydrochloric  acid  • 
make  the  solution  slightly  alkaline  with  sodium  car- 
bonate, and  then  decidedly  acid  with  acetic  acid,  boil,  and 
treat  with  sulphuretted  hydrogen  as  before,  as  the  zinc 
may  carry  down  some  manganese  with  it.  Filter  out  the 
zinc  sulphide,  wash  it  by  decantation  2  or  3  times  with 
hot  water,  and  then,  on  the  filter,  with  sulphuretted  hy- 
drogen water,  into  small  beakers,  changing  them  often,  in 
order  not  to  be  compelled  to  refilter  a  large  amount  of 
fluid,  should  the  zinc  sulphide  run  through  the  filter, 
which  it  is  apt  to  do,  as  soon  as  the  ammonium  chloride  is 
washed  out.  Ammonium  chloride  should  be  washed 
out,  as  it  renders  zinc  carbonate  soluble  to  a  certain  ex- 
tent, when  the  solution  is  afterward  treated  with  sodium 
carbonate.  Should  the  zinc  sulphide  begin  to  run  through 
the  filter,  stop  washing,  and,  into  the  last  turbid  filtrate, 
wash  the  precipitate  from  the  filter  as  completely  as  pos- 
sible with  water,  dry  the  filter,  moisten  it  with  nitric  acid, 
burn  it,  and  add  the  ash  to  the  precipitate.  Then,  add 
concentrated  hydrochloric  acid,  and  a  little  potassium 
chlorate,  and  boil  until  the  zinc  is  dissolved,  and  the  sul- 
phur oxidized.  After  this,  dilute  to  300  c.  c.  for  each  0.500 
gms.  of  zinc  oxide  present  and  heat  to  boiling.  Then,  re- 
move the  heat,  cover  the  vessel,  add  excess  of  sodium  car- 
bonate, and  boil,  to  expel  free  carbonic  acid.  Wash  three 
times  by  decantation  with  hot  water,  boiling  up  each 
time,  and  then  on  the  filter  thoroughly,  and  dry  the  pre- 
cipitate. Brush  the  dry  precipitate  as  completely  as  pos- 
sible from  the  filter  into  a  clock-glass,  burn  the  filter  in 
a  weighed  crucible,  after  moistening  it  with  nitric  acid, 
and  carefully  expelling  the  excess  by  heat,  transfer  the 
precipitate  to  the  crucible,  ignite  again,  cool,  and  weigh 
the  impure  zinc  oxide.  Should  any  zinc  carbonate  adhere 
to  the  vessel  in  which  it  was  precipitated,  dissolve  it  off 
into  a  weighed  dish,  evaporate  to  dryness,  ignite,  weigh. 


VOLUMETRIC   METHODS.  125 

and  add  the  weight  to  that  of  the  main  precipitate.  Dis- 
solve the  ignited  precipitate  in  hydrochloric  acid,  filter 
ont  any  undissolved  silica,  wash,  ignite,  weigh,  and  de- 
duct its  weight  from  that  of  the  weighed  precipitate.  To 
the  filtrate,  add  large  excess  of  pure  potassium  hydrate, 
filter  out  any  metallic  oxides  which  have  been  precipi- 
tated by  the  potassium  hydrate,  dissolve  them  in  hydro- 
chloric acid,  and  repeat  the  treatment.  Deduct  their 
weight,  also.  The  remainder  will  be  zinc  oxide,  from 
which  calculate  metallic  zinc. 

As  sodium  carbonate  sometimes  fails  to  precipitate  all 
the  zinc,  the  filtrate  from  the  zinc  carbonate  should  be 
treated  with  sulphuretted  hydrogen,  and,  if  any  zinc  be 
recovered,  its  weight,  after  proceeding  as  before,  should 
be  added  to  the  first. 

A  great  many  methods,  principally  volumetric,  have 
been  proposed  with  the  view  of  saving  time  and  labor,  in 
the  determination  of  zinc.  Only  one,  that  of  Fahlberg, 
published  in  Fres.,  Zeitsch.,  IV  Hft.  1874,  will  be  given 
here,  with  references  to  others. 

For  the  determination  of  zinc  in  its  ores,  Fahlberg  dis- 
solves them  with  nitric  and  hydrochloric  acids,  adds  an 
excess  of  the  latter,  and  treats  with  a  current  of  hydro- 
sulphuric  acid  to  remove  the  metals  of  Groups  V.  and 
YI.  After  filtering,  the  iron  is  oxidized  with  nitric 
acid,  and,  when  cold,  precipitated  with  ammonium  hydrate, 
+he  zinc  remaining  in  solution.  If  the  iron  should  be 
found  to  contain  zinc,  it  must  be  dissolved  in  hydrochloric 
acid  and  re-precipitated.  The  two  filtrates  are  then  to  be 
added  to  each  other  for  titration.  This  ammoniacal  solu- 
tion is  neutralized  with  hydrochloric  acid,  and  further  10  to 
15  c.  c.  acid  (sp.  gr.  1.12)  is  added,  and  the  titration  with 
the  ferrocyanide  solution  can  then  be  made.  The  normal 
solution  of  potassium  ferrocyanide  is  usually  prepared  so 
that  1  c.  c.  corresponds  to  0.01  gm.  of  zinc,  and  for  this 
purpose  it  is  first  titrated  with  a  solution  of  pure  zinc. 
The  metal  is  first  dissolved  in  hydrochloric  acid,  and  to 


126  .     ZINC   ORE. 

the  solution  ammonium  chloride  to  the  extent  of  five 
times  the  weight  of  the  metal  is  added,  so  as  to  obtain  the 
flakes  of  the  precipitate  as  fine  as  possible,  that  they  may 
not,  while  settling  to  the  bottom,  mechanically  inclose  the 
potassium  ferrocyanide.  In  this  way,  about  0.5  gm.  zinc 
is  to  be  prepared,  and  the  titration  performed  with  a 
burette  provided  with  a  good  glass  stopper,  and  divided 
into  .1  c.  c.  At  first,  large  flakes  are  obtained,  but  as  the 
operation  proceeds,  they  constantly  grow  finer.  After 
each  addition  of  the  ferrocyanide,  a  drop  is  to  be  taken 
from  the  beaker  and  tested  with  solution  of  uranic  ni- 
trate, to  ascertain  whether  the  whole  of  the  zinc  has  been 
converted  into  ferrocyanide,  and  an  excess  of  the  normal 
solution  added.  For  this  purpose,  a  porcelain  slab  is  used, 
which  is  previously  moistened  with  a  row  of  drops  of  the 
uranium  solution.  To  these  drops  is  added,  in  succes- 
sion, after  each  addition  of  the  normal  solution,  a  drop  of 
the  solution  in  course  of  determination  ;  toward  the  close, 
after  every  five  drops  of  normal  solution.  As  long  as 
zinc  remains  in  solution,  only  the  white  flakes  of  ferro- 
cyanide of  zinc  are  seen  on  the  slab,  but  on  the  addition  of 
only  a  very  few  drops  in  excess  of  the  ferrocyanide  a  per- 
manent brown  spot  is  obtained.  With  careful  manipula- 
tion the  greatest  possible  error  is  0.2 — 0.3  per  cent,  but 
even  this  could  be  diminished  one  half  by  the  use  of  a 
normal  solution  of  half  strength.  (See  translation  of 
Fahlberg's  article,  by  Charles  A.  Schaeffer,  Ph.  D.,  in 
Am.  Chem.,  Vol.  Y.,  June,  1875.)  It  has  been  suggested 
that  the  accuracy  of  the  method  is  increased  by  titrating 
the  solution  hot. 

For  other  methods,  consult  Fres.,  Quant.  Anal.,  §248, 
4th  London  Edition ;  also  Crookes's  Select  Methods,  p.  61 ; 
also  Am.  Chem.,  Yol.  II.,  February,  1872. 


CHAPTER    XIX. 

NICKEL   ORE. 

Make  a  qualitative  examination  for  metals  of  Groups  V, 
and  VI. 

Treat  5  gms.  of  the  ore  in  a  small  flask  with  a  mixture 
of  10  c.  c.  of  sulphuric,  10  c.  c.  of  nitric,  and  5  c.  c.  of 
hydrochloric  acids,  all  pure  and  concentrated,  heating 
until  copious  fumes  of  sulphuric  anhydride  are  evolved, 
adding  more  sulphuric  acid  if  necessary,  to  avoid  reducing 
the  mass  to  dryness.  Finally,  cool  the  contents  of  the 
flask,  dilute,  filter,  and  wash  thoroughly. 

If  the  qualitative  examination  has  indicated  the  presence 
of  metals  of  the  higher  groups,  dilute  the  solution  of  5 
gms.  to  500  c.  c,  saturate  with  sulphuretted  hydrogen, 
filter  out  any  precipitated  sulphides,  and  wash  well.  Add 
to  the  filtrate  a  little  hydrochloric  acid  and  potassium 
chlorate,  and  boil  to  oxidize  sulphur  and  ferrous  oxide. 

If  there  be  no  metals  of  the  higher  groups  present,  of 
course  the  treatment  with  sulphuretted  hydrogen,  and 
after  oxidation  with  potassium  chlorate,  is  to  be  omitted. 
Dilute  the  filtrate,  after  boiling,  with  hydrochloric  acid 
and  potassium  chlorate  if  sulphuretted  hydrogen  has 
been  used,  or  the  first  filtrate,  after  decomposing  the  ore 
with  acids,  if  no  sulphuretted  hydrogen  has  been  used,  to 
1  litre,  and  add,  with  constant  stirring,  dilute  ammonia 
until  the  solution  is  alkaline.  Then  filter  out  the  precipi- 
tated ferric  hydrate,  and  wash  slightly.  Dissolve  the  pre- 
cipitate with  dilute  hydrochloric  acid,  and  precipitate 
again  with  dilute  ammonia.  Filter,  wash,  combine  the 
filtrates,  concentrated  to  500  c.  c,  acidify  slightly  with 
acetic  acid,  boil,  and  saturate  with  sulphuretted  hydro- 
gen, continuing  the  boiling  while  introducing  the  gas. 
Filter  out,  and  wash  the  precipitated  sulphides  of  nickel 


128  NICKEL  ORE. 

and  cobalt,  and  wash  them  with  sulphuretted  hydrogen 
water.  Should  any  manganese  oxide  be  present,  it  will  be 
held  in  solution.  To  recover  any  possible  traces  of  nickel 
and  cobalt,  add  a  little  more  acetic  acid  to  the  filtrate, 
and  boil.  Should  any  sulphide  be  recovered  by  this  treat- 
ment, wash  it  and  the  main  precipitate  from  the  filter 
into  a  casserole,  dry  and  burn  the  filters,  add  the  ash  to 
the  precipitates,  and  dissolve  all  with  nitro-hydrochloric 
acid.  Expel  excess  of  acid  by  evaporating  nearly  to  dry- 
ness, dilute,  precipitate  the  oxides  of  nickel  and  cobalt  by 
adding  to  the  solution  an  excess  of  pure  potassium  hy- 
drate, and  heating  for  some  time  nearly  to  boiling,  and 
separate  the  two  metals  by  one  of  the  following  methods. 
(See  Fres.,  Quant  Anal,  §  110— b— *,  p.  188,  and  §  111.) 

The  first  method  is  due  partly  to  Liebig  and  partly  to 
Wohler.  Wash  the  two  oxides  from  the  filter  into  a 
beaker,  run  through  the  filter,  in  order  to  dissolve  what 
adheres,  a  saturated  solution  of  pure  potassium  cyanide, 
into  the  beaker  containing  the  oxides,  and  warm  until  they 
are  dissolved.  The  solution  looks  reddish  yellow.  Heat 
to  boiling  to  remove  the  free  hydrocyanic  acid.  By  this 
process  the  double  cyanide  of  cobalt  and  potassium  in  the 
solution  is  converted,  with  evolution  of  hydrogen,  into 
cobalticyanide  of  potassium,  while  the  double  cyanide  of 
nickel  and  potassium  in  the  solution  remains  unaltered. 
Add  to  the  hot  solution  finely  pulverized  and  elutriated 
mercuric  oxide  (red  oxide),  and  boil.  By  this  operation, 
the  whole  of  the  nickel  is  precipitated,  partly  as  sesqui- 
oxide,  partly  as  cyanide,  the  mercury  combining  with  the 
liberated  cyanogen.  The  precipitate  is  greenish  at  first, 
or,  if  the  mercuric  oxide  has  been  added  in  excess,  yel- 
lowish gray.  Wash  and  ignite.  The  residue  is  oxide  of 
nickel  (MO).     (See  Fres.,  Quant  Anal.,  §  100-14— b.) 

To  determine  the  cobalt  in  the  filtrate,  Wohler  directs  to 
carefully  neutralize  it  with  nitric  acid,  and  add  solution 
of  mercurous  nitrate,  as  long  as  it  produces  a  precipitate 
of     mercury     cobalticyanide.       The     precipitate,     after 


SEPARATION   OF   NICKEL   AND   COBALT.  129 

washing  and  drying,  is  to  be  ignited  with  access  of  air, 
when  it  is  weighed  as  black  oxide  of  cobalt  (Co304).  He 
suggests  that,  on  account  of  its  oxygen  varying  according 
to  the  temperature,  it  is  better  to  reduce  it  by  ignition  in  a 
strong  current  of  hydrogen,  and  weigh  the  metallic  cobalt. 
(See  Wohler'  s  paper  in  Annal.  d.  CTiem.  u.  Pharm.,  LXX., 
"256,  or  his  Mineral  Analysis,  p.  102.  Care  must  be  taken 
in  neutralizing  the  filtrate  before  adding  the  mercurous 
nitrate,  as  the  fluid  must  not  be  acid,  and  must  not  be 
strongly  alkaline.  The  ignited  oxide  of  nickel  is  very  apt 
to  contain  some  impurities ;  consequently,  it  is  better  to 
transfer  it  from  the  crucible  to  a  beaker,  boil  it  with  water, 
throw  it  on  a  filter,  wash,  dry,  ignite,  weigh  again,  and 
subtract  the  loss,  probably  some  adhering  alkali.  Then 
dissolve  it  inaquaregia,  dilute,  filter,  wash,  dry,  ignite,  and 
weigh  any  undissolved  silica,  and  deduct  its  weight  also. 
Finally,  add  to  the  filtrate  a  large  excess  of  ammonia,  filter 
out,  wash,  dry,  ignite,  and  weigh  any  alumina  and  ferric 
oxide  that  may  be  present.  After  deducting  their  weight 
from  that  of  the  original  precipitate,  the  remainder  will  be 
the  true  weight  of  the  oxide  of  nickel.  From  this,  calcu- 
late the  metallic  nickel. 

Another  method  of  separating  the  two  metals  is  by 
means  of  potassium  nitrite,  recommended  by  H.  Rose, 
and  Fresenius  as  the  best.  (See  Fres.,  Quant.  Anal.  §  160- 
9,  p.  366).  Dissolve  the  sulphides  (obtained  after  precipi- 
tating the  basic  acetates,  as  directed  before),  in  aquaregia, 
evaporate  the  solution  nearly  to  dryness,  and  neutralize 
with  potassium  hydrate.  Then  add  a  concentrated  solu- 
tion of  potassium  nitrite  (previously  neutralized  with 
acetic  acid,  and  filtered  from  any  flocks  of  silica  and  alu- 
mina that  may  have  separated)  in  sufficient  quantity,  and 
finally  acetic  acid,  till  any  flocculent  precipitate  that  may 
have  formed  from  excess  of  potassa  has  redissolved,  and 
the  fluid  is  decidedly  acid.  Allow  it  to  stand  at  least  for 
24  hours  in  a  warm  place ;  take  out  a  portion  of  the  super- 
natant fluid  with  a  pipette,  mix  it  with  more  nitrite,  and 


130  NICKEL   ORE. 

observe  whether  a  further  precipitation  takes  place  in  this 
after  long  standing.  If  no  precipitate  is  formed,  the  whole 
of  the  cobalt  has  fallen  down ;  otherwise,  the  small  portion 
must  be  returned  to  the  principal  solution,  some  more 
nitrate  added,  and,  after  long  standing,  the  same  test 
applied.  Finally,  filter  and  wash  the  precipitate  thoroughly 
with  an  aqueous  solution  of  neuti  al  potassium  acetate  (con- 
taining 10  per  cent  of  the  salt),  displace  finally  the  last 
portion  of  solution  of  potassium  acetate  adhering  to  the 
precipitate,  by  means  of  alcohol  of  80  per  cent,  and  dry. 
Then  transfer  the  precipitate  from  the  filter  to  a  clock- 
glass,  incinerate  the  filter  in  a  weighed  crucible,  add  the 
precipitate,  and  gently  ignite  all.  Cool,  moisten  with  sul- 
phuric acid,  cautiously  expel  excess  of  acid,  and  ignite  at 
low  red  heat.  Cool  and  weigh  the  sulphate  of  cobalt  and 
potassium  (2CoSOi+3K2S04),  and  calculate  the  cobalt. 
One  hundred  parts  of  the  residue  are  equivalent  to  18.015 
parts  CoO,  or  14.17  parts  Co.  (See  Fres.,  Quant.  Anal.y 
§81  or  Annal.  d.  Chem.  u.  Pharm.,  CIV.,  309.) 

To  determine  the  nickel,  mix  the  filtrate  with  pure  solu- 
tion of  sodium  or  potassium  hydrate  in  excess,  heat  for 
some  time  nearly  to  ebullition,  decant  3  or  4  times,  boiling 
up  each  time,  filter,  wash  the  precipitate  thoroughly  with 
hot  water,  dry,  and  ignite.  After  weighing  the  precipitate, 
treat  it  as  directed  in  the  first  method,  and  deduct  the 
weight  of  impurities.  (Consult  Fres.,  Quant.  Anal.,  §  110 
p.  187.) 

Another  good  method  of  determining  the  nickel,  and 
cobalt  in  ores,  is  to  decompose  them  in  the  same  manner 
as  directed  above,  remove  any  metals  of  Groups  V.  and 
YI.  with  sulphuretted  hydrogen  in  acid  solution,  filter, 
oxidize  the  filtrate  by  boiling  it  with  hydrochloric  acid 
and  potassium  chlorate ;  dilute  to  about  1  litre.  If  no 
metals  of  the  higher  groups  are  present,  the  treatment 
with  sulphuretted  hydrogen,  and  potassium  chlorate  is  to 
be  omitted,  and  the  original  acid  solution  diluted  to  about 
1  litre.     Then  make  the  solution  alkaline  by  adding  dilute 


131 

ammonia,  and  stirring  constantly.  Filter  out  any  precip- 
itate, dissolve  it  with  hydrochloric  acid,  and  precipitate 
again  in  the  same  way.  Combine  the  nitrates,  concentrate 
them  to  100  c.  c,  add  a  little  ammonia,  transfer  to  a 
weighed  platinum  dish,  and  precipitate  the  nickel  and 
cobalt  together  by  passing  a  strong  galvanic  current,  from 
a  battery  of  2  or  3  Bunsen  elements,  keeping  the  solution 
alkaline  with  ammonia.  The  nickel  and  cobalt  will  be 
precipitated  upon  the  platinum  in  the  form  of  a  metallic 
coating.  When  the  separation  from  the  solution  is  com- 
plete, remove  the  dish,  wash  it  thoroughly  with  hot  water, 
dry  and  weigh  it.  The  increase  in  weight  expresses  the 
combined  weight  of  metallic  nickel  and  cobalt.  It  remains 
to  separate  and  determine  them.  Dissolve  them  with 
nitric  acid ;  determine  them  by  either  of  the  preceding 
methods. 

The  following  method  of  analysis  of  nickel  and  cobalt 
ores  is  from  the  pen  of  Fresenius,  published  in  his  Zeit. 
fur  Anal.  Chem.,  and  translated  by  Prof.  C.  A.  Schaeffer. 
(See  Am.  Chem.,  IV.,  p.  289.) 

The  finely-powdered  mineral  or  metallurgical  product  is 
treated  with  hydrochloric  acid,  with  addition  of  nitric 
acid,  until  all  soluble  matter  has  been  brought  into  solu- 
tion, and  repeatedly  evaporated,  with  addition  of  hydro- 
chloric acid,  almost  to  dryness,  in  order  to  drive  off  the 
excess  of  nitric  acid.  Dilute  hydrochloric  acid  and  water 
are  then  added  to  the  residue,  after  which  it  is  filtered.  If 
the  insoluble  portion  is  not  perfectly  white  it  is  fused 
with  acid  potassium  sulphate,  the  mass  treated  with 
hydrochloric  acid  and  water,  filtered,  and  the  filtrate 
added  to  the  original  solution.  The  metals  of  Groups 
V.  and  YI.  are  next  precipitated  by  hydrosulphuric 
acid.  For  this  purpose,  it  is  well  to  pass  the  gas  through 
the  solution  at  first  at  about  70°  C,  and  afterward  in  the 
cold.  The  filtered  solution  is  then  warmed,  and  the  iron 
©sddized  with  nitric  acid  ;  ammonia  in  excess  in  then  added, 
and  the  impure  ferric  hydrate  filtered  off.    After  washing* 


132  NICKEL   ORE. 

this  is  dissolved  in  hydrochloric  acid,  the  solution  largely 
diluted,  and,  after  addition  of  ammonium  chloride,  a  di- 
lute solution  of  ammonium  carbonate  is  added,  in  the 
cold,  until  a  point  is  reached  where  the  liquid  becomes 
cloudy,  but  no  precipitate  is  visible.  On  standing,  the 
liquid  should  not  again  become  clear,  but  rather  more 
cloudy,  although  the  reaction  at  this  point  must  be  defi- 
nitely acid.  It  is  next  heated  to  boiling,  the  precipitate 
of  basic  oxide  of  iron  is  washed,  first  by  decantation  and 
afterward  on  the  filter  with  boiling  water ;  a  portion  of 
the  precipitate  is  ithen  examined  for  nickel  by  dissolving 
it  in  hydrochloric  acid,  repeating  the  precipitation  as 
basic  oxide,  and  testing  the  filtrate  with  ammonium  sul- 
phide, in  order  to  see  whether  it  is  perfectly  free  from  that 
metal.  If,  in  this  operation,  a  small  amount  of  nickel 
should  still  be  found,  the  whole  precipitate  must  be  dis- 
solved in  hydrochloric  acid,  and  the  iron  again  separated 
as  basic  oxide,  as  above.  The  two,  or,  as  the  case  may  be, 
three  filtrates  which  contain  nickel  and  cobalt  are  next 
acidulated  with  acetic  acid,  and  concentrated  by  evapora- 
tion. If,  by  this  means,  a  trifling  precipitation  of  ferric 
or  aluminic  hydrate  take  place,  the  precipitate  must  be 
filtered  off,  dissolved  in  hydrochloric  acid,  and  again 
separated  with  ammonia  in  excess,  and  this  operation  re- 
peated once  more.  The  filtered  solution,  containing  all 
the  nickel  and  cobalt,  having  been  sufficiently  concen- 
trated, is  treated  with  sodium  carbonate  until  the  reaction 
is  decidedly  alkaline,  acetic  acid  is  then  added  to  acid  re- 
action, and,  to  the  clear  liquid  (30-50  c.  c. ),  a  solution  of 
sodium  acetate  (1 :  10)  is  added.  Hydrosulphuric  acid  is 
then  passed  through  the  solution,  warmed  to  about  70°  C, 
until  the  latter  is  saturated  with  that  gas.  The  separation 
being  completed,  the  precipitate  of  the  sulphides  of  nickel 
and  cobalt  is  filtered,  washed,  and  dried.  The  filtrate  is 
concentrated  by  evaporation  ;  hydrosulphuric  acid,  am- 
monium sulphide,  and  acetic  acid  are  added  to  it,  and 
thus  frequently  a  little  more  of  the  sulphides  of  nickel  and 


ERESENIUS'S   METHOD.  '  133 

cobalt  is  obtained.     It  is  well  to  test  the  nitrate  in  this 
way  once  again,  in  order  to  be  quite  sure  that  the  whole  of 
the  nickel  and  cobalt  has  been  obtained  as    sulphides. 
The  dried  sulphides  of  nickel  and  cobalt,  together  with 
the  filter  ash,    are  now  treated  with  hydrochloric   acid, 
with  addition  of  nitric  acid,  until  all  has  been  dissolved, 
the  solution  evaporated  with    addition  of    hydrochloric 
acid  in  order  to  drive  off  the   nitric  acid,  diluted  with 
water,  filtered,  and  the  nickel  and  cobalt  precipitated  with 
pure  potassium  hydrate  in   a  large  platinum  dish.     The 
precipitate  obtained  must  be  very  thoroughly  washed  by 
decantation  afterward  on  the  filter,   with  boiling  water, 
dried,  incinerated  and  heated  to  bright  redness  in  a  Rose 
crucible,  in  a  current  of  pure  hydrogen,  until  the  weight  re- 
mains constant.      The  metallic  nickel  and  cobalt  are  next 
treated  in  the  crucible  with  boiling  water.     Should  this 
show  an  alkaline  reaction  or  the  presence  of   chlorine  or 
sulphuric  acid,  or  yield  a  residue  when  evaporated  on 
platinum  foil,  the  metals  must  be  exhausted  with  boiling 
water,    heated    in    a    current    of    hydrogen,  and    again 
weighed.     The  metals  are  now  dissolved  in  hydrochloric 
acid,  after  which  a  small  amount  of  silicic  acid  usually  re- 
mains.    This  is  to  be  collected  on  a  filter,  burned,  and 
weighed.     The  hydrochloric  acid  solution  is  nearly  neu- 
tralized with  ammonia  ;  ammonium  carbonate  is  added  in 
excess,  and  the  liquid  slightly  warmed  for  some  time.     A 
trifling  precipitate  of  ferric  and  aluminic  hydrates,  which 
in  most  cases  is  obtained,  is  filtered,  dissolved  in  hydro- 
chloric acid,  again  precipitated,  and  ignited,  first  in  the  air 
and  then  in  a  current  of  hydrogen.      Its  weight,  together 
with  that  of  the  silicic  acid,  is  then  to  be  subtracted  from 
the  original  weight  of  the  metals.      As  can  easily  be  seen, 
it  will  in  most  cases  be  allowable,  and  a  great  saving  of 
time,  to  incinerate  the  little  filter  containing  the  silicic 
acid,  and  that  containing  the  ferric  and  aluminic  hydrates 
in  the  same  small  crucible,  and  then,  after  treatment  with 
hydrogen,  to  weigh  all  these  impurities  together.    Should, 


134  NICKEL  ORE. 

however,  the  ash  of  these,  in  consequence  of  the  presence 
of  a  small  amount  of  cobalt,  appear  bluish,  it  must  be 
fused  with  an  alkaline  carbonate,  and  the  silicic  acid,  etc., 
thus  obtained  be  perfectly  pure. 

If  the  ore  or  metallurgical  product  contain  zinc,  the 
nickel  and  cobalt  obtained  by  the  above  method  would  be 
contaminated  with  that  metal,  since  zinc  cannot  be  entirely 
removed  either  by  the  precipitation  of  the  hydrates  with 
excess  of  potassium  hydrate,  or  by  the  reduction  of  the 
oxides  in  a  current  of  hydrogen.  In  this  case,  the  hydro- 
chloric acid  solution  of  the  metals  precipitated  by  ammo- 
nium sulphide  is  evaporated  to  a  small  volume ;  and  pure, 
finely-crystallized  ammonium  chloride  is  added  to  it  in 
such  quantity  that,  for  0.2  gm.  oxide  of  zinc,  there  shall  be 
about  5  gms.  ammonium  chloride.  It  is  then  evaporated 
to  dryness  on  a  water-bath,  and  carefully  heated,  until  all 
the  ammonium  chloride,  and  with  it  all  the  zinc,  is  driven 
off.  The  residue,  which  consists  of  metallic  nickel  and 
cobalt,  is  dissolved  in  hydrochloric  acid,  with  the  addition 
of  nitric  acid,  the  greater  part  of  the  excess  of  free  acid 
driven  off,  and  the  oxides  precipitated  with  potassium 
hydrate,  and  further  treated  exactly  according  to  the 
above  method. 

If  nickel  and  cobalt  are  to  be  determined  separately, 
the  ammoniacal  filtrates,  obtained  after  separation  of  the 
contaminating  substances,  are  evaporated  to  dryness,  the 
ammonium  compounds  are  driven  off  by  gentle  heat,  the 
residue  dissolved  in  hydrochloric  acid,  with  addition  of 
nitric  acid,  and  if  much  nickel  and  little  cobalt  are  present, 
the  latter  is  separated  by  means  of  potassium  nitrite.  If, 
on  the  contrary,  much  cobalt  and  little  nickel  are  present, 
it  is  found  more  advisable  to  add,  to  the  solution  of  the 
chlorides,  potassium  cyanide  in  excess,  and  to  precipitate 
the  nickel  as  the  black  hydrate  oxide  of  nickel,  by  warm- 
ing with  bromide  after  the  addition  of  the  potassium 
hydrate.  In  the  first  case,  the  potassio-cobaltic  nitrite, 
and  in  the  second,  the  hydrated  oxide  of  nickel,  is  dis- 


IMPURITIES  IJST  PRECIPITATES.  135 

solved  in  hydrochloric  acid,  precipitated  with  potassium 
hydrate,  and  determined  in  the  metallic  condition.  In 
these  determinations,  the  weighings  must  be  followed  by 
an  examination  for  silicic  acid,  and  impurities  insoluble  in 
ammonium  carbonate. 


Note. — For  the  determination  of  nickel  and  cobalt  by  the  battery  see  Luckow, 
Fres.,  Zeitschrift  fur  Anal.  Chem.,  XIX.,  p.  1.,  orDingler's  Polyt,,  vols.  CLXXVII 
and  CLXVIII.  Organic  salts,  as  acetates,  etc.,  aid  this  precipitation  (Luckow). 
Ammonium  chloride  in  the  solution  interferes  with  this  separation  according  to 
Luckow  (Fres.,  Zeitschrift,  XL,  11),  Wrightson  (ibid,  XV.,  297),  Schroeder  (ibid, 
XVI.,  344),  Beilstein  (Berichte  Dent.  Chem.  Oesell,  XI.,  1715),  Riche  (Comptes 
Bend.,  LXXXV.,  326)  and  others. 


CHAPTER  XX. 

COPPER     ORE. 

For  directions  for  making  a  complete  analysis  of  cop- 
per ore,  consult  Fres.,  Quant.  Anal.,  §  242.  It  is  pro- 
posed here  to  give  directions  for  the  separation  and  de- 
termination of  copper  alone. 

The  first  step  is  to  make  a  careful  qualitative  examina- 
tion of  the  ore.  Then  introduce  1  gm.  of  finely-pulverized 
ore  into  a  flask  holding  about  200  c.  c. ,  add  5  c.  c  nitric, 
2  c.  c.  hydrochloric,  and  10  c.  c.  sulphuric  acid  (the  acids 
should  all  be  pure  and  poncentrated),  boil  until  all  the 
nitric  acid  is  expelled,  and  dense  white  fumes  of  S03  are 
evolved.  The  nask  should  be  filled  with  them.  Then 
cool,  dilute  with  about  50  c.  c.  of  water,  filter,  and  wash 
with  about  75  c.  c.  more.  Digest  the  residue  with  nitric 
and  hydrochloric  acids,  and  if  the  solution  gives  any 
reaction  for  copper,  add  sulphuric  acid  and  treat  as  before. 
Treat  a  third  time,  if  necessary. 

If  the  ore  be  very  poor,  more  than  1  gm.  should  be 
taken,  and  treated  with  a  corresponding  amount  of  the 
three  acids. 

Should  no  metals  of  Group  VI.  or  any  of  Group  V. 
besides  copper  be  present,  dilute  the  solution  to  200  c.  c. , 
or  if  it  already  exceeds  that  volume,  concentrate  to  200 
c.  c,  and  divide  into  two  exactly  even  parts.  Introduce 
each  into  a  weighed  platinum  dish,  and  precipitate  the 
copper  by  a  galvanic  current,  the  dishes  being  connected 
with  the  zinc  or  negative  pole  of  a  battery  (consisting  of  at 
least  two  Bunsen  elements)  by  resting  on  a  coil  of  the  wire 
or  a  copper  disk  to  which  the  wire  is  soldered,  while  the 
fluid  in  the  dishes  is  connected  with  the  positive  pole 
by  a  wire  attached  to  platinum  foils  which  hang  in 
the  fluid.  When  the  copper  is  entirely  precipitated 
(which  can  be  determined  by  testing  a  few  drops  of  the 


ELECTROLYTIC   DETERMINATION.  137 

fluid  with  sulphuretted  hydrogen  water),  pour  out  the 
contents  of  the  dishes  into  a  beaker,  wash  them  (two  or 
three  times)  with  hot  water  in+o  the  same  beaker,  and  then 
with  alcohol,  to  displace  the  water,  decanting  the  alcohol 
off,  as  completely  as  possible,  into  another  vessel.  Then 
dry  the  dishes  over  a  low  flame  until  the  small  quantity 
of  alcohol  adhering  to  the  copper  is  expelled,  and  weigh 
them.  The  increase  in  weight  represents  the  weight  of 
metallic  copper.  The  difference  in  weight  of  copper  in  the 
two  dishes  should  not  exceed  one  tenth  of  one  per  cent. 
Should  it  do  so,  another  determination  must  be  made. 

In  evaporating  off  the  alcohol,  the  dishes  should  not  be 
allowed  to  become  so  hot  that  they  cannot  be  carried  to 
the  balance  on  the  naked  hand,  and  be  cool  enough  to 
weigh  in  five  minutes.  It  is  unnecessary  to  place  them  in 
a  desiccator.  i 

The  copper  should  be  bright  red  in  color,  free  from 
all  dark  spots,  and  so  firmly  attached  to  the  dish  as  not  to 
be  washed  off  by  water.  The  formation  of  spongy  copper 
is  an  indication  that  too  much  ore  has  been  used  for  the 
capacity  of  the  dish,  or  that  the  current  has  been  too 
intense. 

This  is  the  best  method  in  most  cases. 

To  prove  the  accuracy  of  this  method,  Mohr  mixed  1 
gm.  of  pure  metallic  copper  with  0.5  gm.  of  gold,  silver, 
platinum,  tin,  lead,  iron,  zinc,  nickel,  cobalt,  bismuth 
arsenic,  uranium,  mercury,  molybdenum,  antimony,  sul- 
phur, silica,  and  calcium  phosphate,  treated  the  mixture  in 
a  similar  manner,  precipitating  the_  copper  in  a  platinum 
dish  with  metallic  zinc  instead  of  the  galvanic  current,  and 
recovered  0.996  gm.  of  copper.  In  more  than  20  determi- 
nations of  copper  in  various  combinations,  the  average 
amount  of  the  metal  obtained  by  this  method  was  99.7  per 
cent  of  the  actual  quantity  present. 

If  arsenic  or  antimony  be  present  in  the  ore,  it  is  safer 
to  remove  them  by  saturating  the  solution  with  sulphu- 
retted   hydrogen,   making    it    alkaline    with    potassium 


138  COPPEE  ORE. 

hydrate,  and  warming  gently  for  some  time  to  dissolve 
the  sulphides  of  arsenic  and  antimony.  Filter  and  wash 
the  copper  sulphide,  which  may  contain  some  other  sul- 
phides of  metals  of  Group  V.  If  it  does  not  contain  them, 
or  only  lead  sulphide,  dissolve  in  nitric  acid,  add  sul- 
phuric acid,  evaporate  to  dense  fumes  of  S03,  cool,  dilute, 
filter  out  any  insoluble  residue,  and  proceed  to  determine 
the  copper  electrolytically,  as  directed  above.  When 
other  metals  of  Group  V.  are  present,  treat  the  sulphides 
with  pure  potassium  cyanide,  which  will  dissolve  the  cop- 
per sulphide,  and  leave  the  others  undissolved.  Then 
treat  the  solution  with  nitric  acid,  boil  to  expel  hydro- 
cyanic acid,  add  sulphuric  acid,  heat  to  expel  nitric  acid, 
and  proceed  as  before. 

Determination  as  cuprous  sulphide  (Cu2S) : 

Instead  of  dissolving  the  copper  sulphide  in  nitric  acid, 
and  evaporating  the  solution  after  addition  of  sulphuric 
acid,  dry  it,  transfer  the  precipitate  to  a  watch-glass,  burn 
the  filter  in  a  weighed  porcelain  crucible  provided  with  a 
perforated  cover  (known  as  Rose's  crucible),  add  the  pre- 
cipitate and  some  pure  powdered  sulphur,  and  burn  in  a 
current  of  hydrogen,  over  a  blast-lamp.  Weigh  as  Cu2S. 
(Compare  H.  Rose's  Quant.  Anal.,  pp.  105  and  255,  chap- 
ter on  copper ;  also,  Fres.,  Quant.  Anal.,  §  119-3,  p.  230, 
and  Jour.f.  PraM.  Chem.,  CVIL,  110,  andLXIL,  252.  The 
results  are  very  accurate.  The  method  is  the  best  one, 
where  the  electrolytic  method  cannot  be  conveniently 
applied. 

Determination  as  oxide : 

Decompose  the  ore  as  directed  in  the  first  instance,  and, 
after  separating  the  copper  from  other  associated  metals, 
as  directed  above,  add  to  the  solution,  after  evaporating 
off  excess  of  acid,  and  heating  to  boiling,  dilute  solution 
of  pure  potassium  or  sodium  hydrate,  in  excess,  and  con- 
tinue to  boil  until  the  cupric  hydrate,  which  is  pale  blue, 
is  converted  into  brownish  black  cupric  oxide.  Allow  the 
precipitate  to  settle,  filter,  wash  by  decantation  with  boil- 


DETERMINATION   AS    OXIDE.  139 

ing  water  several  times,  transfer  to  the  filter,  wash  well 
with  boiling  water,  dry,  ignite  intensely,  and  weigh.  Then 
add  a  few  drops  of  nitric  acid,  evaporate  off  excess  of  acid, 
ignite  cautiously,  cool,  and  weigh.  From  the  weighed 
cupric  oxide  calculate  metallic  copper. 

The  action  of  reducing  gases  must  be  carefully  avoided. 
The  addition  of  nitric  acid,  and  second  ignition  is  to  over- 
come any  difficulty  arising  from  this  cause.  Consult 
Fres.,  Quant.  Anal.,  §  119 — 1 — a.,  for  precautions  to  be 
observed  and  difficulties  to  be  encountered. 

There  are  various  volumetric  methods  of  determining 
copper,  for  some  of  which  consult  Fres.,  Quant.  Anal., 
§  119,  p.  225. 


CHAPTER    XXI. 

GERMAN   SILVER. 

The  metals  to  be  looked  for  usually  are  copper,  nickel, 
zinc,  and  iron,  which  last  is  sometimes  added  to  make 
the  metal  white.  Lead  is  sometimes  found  in  small 
quantity. 

Introduce  0.500  gm.  of  the  alloy  into  a  200  c.  c.  flask, 
add  5  c.  c.  of  concentrated  nitric  acid,  and  15  c.  c.  of  water, 
and  heat  until  the  alloy  is  dissolved.  Then  cool,  add  10 
c.  c.  of  concentrated  sulphuric  acid,  and  heat  until  dense 
fumes  of  S03  are  evolved.  Cool,  dilute  to  50  c.  c, 
and  filter  out  lead  sulphate,  if  necessary.  Divide  the 
filtrate  into  2  equal  parts,  and  determine  the  copper  in  each 
electrolytically,  as  directed  in  the  analysis  of  copper  ore. 
Combine  the  solutions  (after  precipitating  the  copper)  to- 
gether with  the  washings  (after  boiling  out  the  alcohol 
from  them),  add  sodium  carbonate  until  the  fluid  is  slightly 
alkaline,  and  then  acetic  acid  until  it  is  acid,  and  precipi- 
tate basic  ferric  acetate  as  usual.  Dissolve  the  precipitate 
in  hydrochloric  acid,  re-precipitate  the  ferric  hydrate  by 
amnionic  hydrate,  filter,  dry,  ignite,  and  weigh,  and  calcu- 
late it  to  metallic  iron. 

To  the  filtrate,  add  pure  potassium  hydrate  in  large  ex- 
cess. Nearly  all  the  zinc  will  be  held  in  solution,  while 
the  nickel,  with,  perhaps,  a  little  zinc,  will  be  precipitated. 
Allow  the  precipitate  to  settle,  decant  the  clear  fluid  into 
another  vessel,  and  add  to  the  precipitate  a  concentrated 
and  filtered  solution  of  pure  potassium  cyanide,  and  digest 
over  heat,  until  the  precipitate  goes  into  solution.  It 
sometimes  happens  that  a  portion  of  it  resists  the  action 
of  the  cyanide.  When  such  is  the  case,  filter  it  out,  and 
as  it  contains  no  zinc,  dissolve  it  in  hydrochloric  acid  and 
potassium  chlorate,  and  reserve  it  to  be  added  to  the  solu- 


ZINC — NICKEL — IRON.  141 

tion  containing  the  nickel  after  precipitating  the  zinc. 
Combine  the  other  solutions  containing  zinc  and  nickel, 
neutralize  with  hydrochloric  acid,  leaving  the  fluid  only 
slightly  alkaline,  add  potassium  sulphide  until  all  the  zinc 
is  precipitated,  filter,  and  determine  the  zinc  as  directed  in 
analysis  of  zinc  ore. 

Add  to  the  filtrate  from  the  zinc  sulphide,  the  solution 
of  the  small  portion  which  resisted  the  action  of  potas- 
sium cyanide,  add  more  hydrochloric  acid,  if  necessary, 
and  boil,  to  decompose  the  cyanides,  and  expel  cyanogen. 
Then  make  the  solution  strongly  alkaline  with  ammonia, 
filter  out  any  ferric  hydrate,  calculate  it  to  metallic  iron, 
and  add  the  per  cent  to  that  obtained  from  the  acetate. 
In  the  ammoniacal  filtrate  from  the  ferric  hydrate,  deter- 
mine the  nickel  electrolytically,  as  in  the  analysis  of 
nickel  ore. 

As  the  above  operations  may  introduce  such  amounts 
of  salts  as  to  interfere  with  concentration  for  the  battery 
precipitation,  it  may  be  preferable  to  precipitate  out  the 
nickel  and  redissolve.  In  such  a  case  add  ammonium 
sulphide — stir  it  in  well — render  just  acid  with  acetic 
acid,  and  allow  the  solution  to  stand  for  some  time.  Then 
decant  through  a  filter,  allowing  as  little  of  the  precipitate 
as  possible  to  get  upon  the  filter  ;  dissolve  the  precipitate 
in  hot  nitric  acid,  destroy  the  carbon  of  the  filter  by  fusing 
with  a  small  amount  of  alkaline  nitrate,  and  add  to  the 
solution  of  the  precipitate.  The  neutralization  by  ammo- 
nia, etc.,  may  then  be  conducted  as  usual. 

If  the  analysis  be  made  entirely  without  the  use  of  a  bat- 
tery, after  dissolving  the  alloy,  and  removing  any  lead  as 
above,  precipitate  the  copper  as  sulphide,  ignite  it,  after 
adding  sulphur,  in  a  current  of  hydrogen,  and  weigh  the 
ignited  precipitate  as  cupreous  sulphide.  (See  analysis  of 
copper  ore.) 

Boil  the  filtrate  from  the  copper  sulphide,  with  potas- 
sium chlorate,  and  determine  the  zinc,  nickel,  and  iron  as 
above. 


CHAPTER    XXII. 


GALENA. 


Treat  1  gm.  with  fuming  nitric  acid,  and  sulphuric  acid. 
Note  1. 


Residue  (a). 
Lead  sulphate  and  gangue.  Note  2. 


Residue  (5). 
Lead  carbonate 
and  gangue.  Note 
2. 


Solution  (b). 
Alkaline  sulphate 
reserve.      Treat 
withH2S.    Note  2 


Filtrate  (a). 
Silver  and  other  metals. 


Note  4. 


Filtrate  (e). 
Iron,  zinc,  cop- 
per, etc.    Note  4. 


Precipitate  (e). 
Silver.    Note  4. 


Solution  (c). 
Lead  acetate.     Note  3. 

Precipitate  (d). 
Lead  sulphide.    Note  3. 


Residue  (c). 
Insoluble  gangue.    Note  2. 


Filtrate  (d). 
To  be  combined  with  solution  (5> 
residue  (c),  and  filtrate  (e).      Notes 
1 3  and  4. 

Notel. — Introduce  into  a  flask  holding  about  200  c.  c,  1 
gm.  of  finely  pulverized  galena,  previously  dried  at  100° 
C.j  add  4  or  5  c.  c.  of  red  fuming  nitric  acid,  and  cover 
with  a  watch-glass.  After  the  violent  action  is  over,  heat 
on  a  water-bath  for  some  time,  to  oxidize  the  sulphur. 
After  the  sulphur  is  oxidized,  add  3  or  4  c.  c.  of  sulphuric 
acid  previously  diluted  with  3  or  4  c.  c.  of  water,  and  heat 
over  a  burner  until  the  nitric  acid  is  expelled,  and  dense 
white  fumes  of  S03  appear.  Then  cool,  dilute  cautiously 
with  about  50  c.  c.  of  water,  filter,  and  wash  the  residue 
containing  lead  sulphate  and  gangue,  with  about  100  c.  c. 
of  water  containing  1  per  cent  of  sulphuric  acid,  and  then 
with  30  or  40  c.  c.  of  alcohol. 

There  will  be  a  residue  (a)  on  the  filter  containing  lead 
sulphate  and  gangue,  and  a  filtrate  (a),  containing  silver, 
and  other  metals. 

Note  2. — Wash  residue  (a)  into  a  beaker,  add  about  50 
c.  c.  of  strong  solution  of  ammonium  carbonate,  and  digest 


LEAD — SILVER.  143 

on  a  water-bath,  with  frequent  stirring  for  10  or  12  hours, 
to  convert  the  lead  sulphate  into  carbonate.  Filter,  and 
wash  well  with  a  solution  of  ammonium  carbonate,  and 
then  with  hot  water  to  dissolve  out  all  alkaline  sulphate. 

There  will  be  a  residue  (b)  of  lead  carbonate  and  gangue, 
and  a,  filtrate  (b)  of  alkaline  sulphate.  Dissolve  the  lead 
carbonate  through  the  filter  with  hot  acetic  acid,  keeping  it 
covered  until  effervescence  ceases,  and  is  not  renewed  upon 
the  further  addition  of  acetic  acid.  Wash  thoroughly,  to 
remove  all  lead  acetate  from  the  gangue  remaining  on  the 
filter.  Treat  filtrate  (b)  with  HaS,  and  add  precipitate  to 
precipitate  (d). 

There  will  be  a  solution  (c)  of  lead  acetate  and  a  residue 
(c)  of  insoluble  siliceous  gangue. 

Note  3. — Saturate  solution  (c)  with  sulphuretted  hydro- 
gen, filter,  and  wash  with  hot  water.  There  will  be  a  pre- 
cipitate (d)  of  lead  sulphide,  and  a  filtrate  (d)  which  is  to 
be  combined  with  solution  (5),  residue  (c),  and  filtrate  (e). 
Wash  the  lead  sulphide,  or  precipitate  (d\  into  a  cas- 
serole, dry  the  filter,  burn  it  in  a  porcelain  crucible,  cftor 
moistening  it  with  a  few  drops  of  nitric  acid,  treat  the  ash 
with  a  little  dilute  nitric  acid,  and,  when  it  is  dissolved, 
wash  the  solution  into  the  same  casserole,  add  3  or  4  c.  c. 
of  sulphuric  acid,  and  heat  until  fumes  of  S03  appear. 
Then  cool,  dilute  with  30  or  40  c.  c.  of  water,  filter,  wash 
with  about  50  c.  c.  of  water  containing  1  per  cent  of  sul- 
phuric acid,  and  finally  with  about  the  same  quantity  of 
alcohol.  Dry  the  filter  and  contents  at  a  moderate  heat 
(not  over  100°  C),  and,  when  dry,  brush  the  contents 
into  a  glass  as  completely  as  possible,  burn  the  filter  in  the 
way  directed  above,  in  a  weighed  porcelain  crucible,  add 
to  the  ash  5  or  6  drops  of  nitric  acid  and  2  or  3  drops  of  sul- 
phuric acid,  evaporate  the  excess  of  acid,  add  the  precipi- 
tate, and  ignite  all.  Cool  and  weigh  the  lead  sulphate, 
and  calculate  the  lead. 

Note  4. — To  filtrate  (a),  containing  the  silver,  add,  after 
boiling  out  the  alcohol,  about  1  c.  c.  of  hydrochloric  acid. 


J44  GALENA. 

Should  any  turbidity  of  the  fluid  be  occasioned  by  the 
hydrochloric  acid,  let  the  solution  stand  for  some  hours  in 
a  warm  place,  until  the  precipitate  settles,  filter,  and  wash. 

There  will  be  a  precipitate  (e)  of  silver  chloride,  and  a 
filtrate  (e),  containing  other  metals. 

Dry  the  precipitate,  remove  it,  if  possible,  from  the  filter, 
burn  the  latter  in  a  weighed  porcelain  crucible,  add  to  the 
ash  a  few  drops  of  nitric  acid  and  hydrochloric  acid, 
evaporate  to  dryness,  add  the  precipitate,  and  fuse  at  a 
low  red  heat.  (See  analysis  of  barium  chloride. )  From 
the  weight  of  silver  chloride,  calculate  the  silver. 

To  filtrate  (e\  after  adding  solution  (&),  residue  (c),  and 
filtrate  (d\  add  excess  of  sodium  carbonate,  and  a  little 
sodium  nitrate,  evaporate  to  dryness  in  a  platinum  dish, 
fuse,  and  determine  the  other  constituents  of  the  ore. 

Note  5. — It  is  better  to  determine  the  sulphur  in  a  sepa- 
rate portion.  For  this  purpose,  heat  1  gm.  of  the  finely 
pulverized  galena  in  a  large  porcelain  crucible,  at  100°  C, 
with  a  strong  solution  of  potassium  hydrate,  for  an  hour, 
and  pass  a  slow  current  of  chlorine  through  the  fluid.  The 
sulphur  will  be  converted  into  sulphuric  acid.  Then  filter, 
wash,  acidify  the  filtrate  with  hydrochloric  acid,  and  pre- 
cipitate the  sulphur  as  barium  sulphate,  as  usual.  Bro- 
mine may  be  used  to  oxidize  the  sulphur,  instead  of  chlor- 
ine. (See  Jour.  f.  PraM.  Chem.,  LXL,  134,  and  Compt. 
Rend.,  37,  835.) 

Note  6. — If  it  be  desired  to  determine  a  small  quantity 
of  silver  in  the  presence  of  a  large  quantity  of  lead,  by  a 
wet  method,  consult  Fresenius's  Analysis  of  Refined  Lead, 
mZeits.  fur  Anal.  Chem.,  Yol.  VIII. ,  1869. 


Note. — The  ammonium  carbonate  used  in  Note  2  should  be  a  solution  of  the 
solid  salt  made  without  addition  of  ammonium  hydrate.  A  more  rapid  method 
consists  in  using  a  solution  of  ammonium  citrate  with  ammonia,  which  will  at  once 
dissolve  the  lead  sulphate.  From  this  solution,  neutralized  by  sulphuric  acid,  the 
lead  may  be  precipitated  by  HaS,  and  the  precipitate  converted  into  sulphate  by 
oxidation  with  nitric  acid,  and  subsequent  treatment  with  sulphuric  acid. 


CHAPTER    XXIII. 

TIN    ORE. 

There  are  many  methods  proposed  for  the  determination 
of  tin  in  ores.  Probably,  the  fnsion  of  the  ore  with  sul- 
phur and  sodium  carbonate  is,  as  Rose  remarks,  p.  392, 
the  best.  It  requires,  however,  the  exercise  of  great  care 
and  judgment  to  make  it  successful.     It  is  as  follows  : 

Fuse  1  gm.  of  rich  ore,  very  finely  pulverized,  with  3 
parts  of  sulphur,  and  3  parts  of  dry  sodium  carbonate 
(after  mixing  the  ore  and  flux  thoroughly),  in  a  large 
porcelain  crucible,  for  about  one  hour,  over  a  Bunsen 
burner.  The  heat  should  not  be  too  great,  or  continued 
too  long,  as,  under  such  circumstances,  the  sulphide  of  tin 
may  be  oxidized  and  become  insoluble  when  the  fused 
mass  is  treated  with  water.  By  the  fusion,  sulphides  of 
tin  and  sodium  are  produced,  and,  upon  adding  water,  the 
tin  sulphide  should  go  into  solution  in  the  sodium 
sulphide,  as  sodium  sulpho-stannate,  and  will — if  the  fusion 
has  been  properly  conducted.  After  fusing  as  directed, 
cool,  place  the  crucible  in  a  casserole,  add  hot  water,  and 
digest  on  a  water-bath  until  the  fused  mass  is  disinte- 
grated and  removed  from  the  crucible.  Then  filter,  wash 
thoroughly  with  hot  water,  and  acidulate  with  sulphuric 
acid,  to  precipitate  the  tin  sulphide.  Allow  the  sulphide 
to  settle  completely,  in  a  warm  place,  pour  the  clear  fluid 
on  a  filter,  wash  4  or  5  times  by  decantation,  and  then 
moderately  on  the  filter  with  hot  water.  Should  the  pre- 
cipitate show  an  inclination  to  run  through  the  filter, 
wash  with  solution  of  ammonium  acetate  (Bunsen).  Put 
the  filter,  with  the  not  yet  quite  dry  precipitate  on  it,  into  a 
weighed  porcelain  crucible,  and  apply  a  very  gentle  heat, 
with  free  access  of  air,  until  the  odor  of  sulphurous  acid  is 
no  longer  perceptible.   Increase  the  heat  now  gradually,  to 


146  TIN   ORE. 

a  high,  degree  of  intensity,  and  treat  the  residue  repeat- 
edly with  some  carbonate  of  ammonia,  in  order  to  insure 
the  complete  expulsion  of  the  sulphuric  acid  which  may 
be  present.  Were  you  to  apply  a  very  intense  heat  from 
the  beginning,  fumes  of  stannic  sulphide  would  escape, 
which  burn  to  binoxide  (H.  Rose,  p.  393).  The  residue 
left  after  the  first  fusion  and  solution,  should  be  fused 
again,  and  treated  in  the  same  way  ;  and  even  a  third  and 
fourth  time,  or  until  no  more  tin  can  be  recovered. 

After  weighing  the  stannic  oxide,  it  shou]d  be  examined 
for  silica.  To  do  this,  weigh  out  a  portion,  and  fuse  it 
with  3  or  4  parts  of  a  mixture  of  equal  weights  of  sodium 
and  potassium  carbonates,  boil  with  water,  filter,  wash, 
acidulate  the  filtrate  with  hydrochloric  acid,  and  should 
silica  separate,  filter,  and  reserve  the  filter  and  con- 
tents. Then  precipitate  the  tin  with  sulphuretted  hydro- 
gen, filter  out  the  sulphide,  and  treat  the  filtrate  as  usual 
for  silica,  finally  filtering  through  the  reserved  filter, 
already  containing  some  silica.  Calculate  the  silica  thus 
found,  to  the  whole  amount  of  stannic  oxide,  and,  after 
deducting  it,  calculate  the  metallic  tin. 

Examine  the  residue  left  (after  fusing,  and  filtering  out 
the  solution  of  alkaline  stannate  as  directed  above)  for 
iron,  by  dissolving  it  in  hydrochloric  acid  and  a  few  drops 
of  nitric  acid,  and  precipitating  the  ferric  hydrate  with 
excess  of  ammonia.  Should  any  be  found,  it  must  be 
calculated  to  the  whole  amount  of  stannic  oxide  first 
weighed,  and  deducted  from  it,  as  was  the  silica.  It  must 
be  calculated  also  to  metallic  iron,  and  the  per  cent  added 
to  that  found  elsewhere. 


CHAPTER    XXIV. 

BRONZE. 

The  metals  to  be  looked  for  are  copper,  tin,  lead,  zinc, 
and  iron. 

Dissolve  1  gm.  of  the  alloy,  in  a  small  covered  beaker, 
in  a  mixture  of  2  c.  c.  of  nitric  acid,  8  c.  c.  of  hydro- 
chloric acid,  and  10  c.  c.  of  water,  dilute  to  200  c.  c,  heat 
gently,  add  crystals  of  sodium  carbonate  until  a  distinct 
precipitate  forms,  and  boil  until  the  basic  carbonate  of 
copper  turns  black.  Then  cool,  add  nitric  acid,  drop  by 
drop,  until  the  reaction  is  distinctly  acid,  and  digest  for 
several  hours  at  a  gentle  heat  until  the  stannic  oxide  is 
white.  Then  filter  it  out,  wash,  dry,  ignite  strongly,  and 
weigh  it.  The  stannic  oxide  must  then  be  examined  for 
silica  and  iron  (as  directed  in  the  analysis  of  tin  ore), 
which  are  to  be  deducted  before  calculating  the  tin.  (See 
Fres.,  Quant  Anal.,  §  164— B— 4— a,  p.  391.) 

The  ignited  stannic  oxide  may  be  purified,  by  first  treat- 
ing it  with  sulphuric  acid  and  ammonium  fluoride  (the 
silica  being  determined  by  loss),  and  then  fusing  it  with 
the  two  carbonates,  as  in  analysis  of  tin  ore,  dissolv- 
ing and  filtering  out  the  stannate,  and  in  the  residue  deter- 
mining the  ferric  oxide,  to  be  deducted  from  the  stannic 
oxide,  and  also  calculated  to  metallic  iron,  the  per  cent  of 
which  is  to  be  added  to  that  found  elsewhere. 

Evaporate  the  filtrate  from  the  stannic  oxide,  after 
adding  about  10  c.  c.  of  sulphuric  acid,  until  fumes  of  SOs 
are  evolved,  dilute,  filter  out  lead  sulphate,  and  calculate 
lead.     (See  analysis  of  galena.) 

After  filtering  out  the  lead  sulphate,  and  washing,  deter- 
mine the  copper  in  the  filtrate  electrolytically.  (See 
analysis  of  copper  ore.) 

In  the  residual  fluid,  after  extracting  the  copper,  precip- 


148  BRONZE. 

itate  the  zinc  by  sodium  carbonate,  and  proceed  as  directed 
in  the  analysis  of  zinc  ore.  Dissolve  the  weighed  zinc 
oxide  in  hydrochloric  acid,  filter  out  and  determine  any 
residual  silica,  and  deduct  its  weight  from  that  of  the 
oxide.  Then  add  to  the  filtrate,  excess  of  pure  potassium 
hydrate ;  filter  out  and  wash  the  ferric  hydrate,  dissolve  it 
in  hydrochloric  acid,  and  precipitate  again  with  potassium 
hydrate,  filter,  wash,  dry,  ignite,  and  weigh  the  ferric 
oxide,  which  is  also  to  be  deducted  from  the  first  weight 
of  zinc  oxide.  The  remainder,  after  deducting  the  weight 
of  silica,  and  that  of  ferric  oxide,  is  to  be  calculated  to 
zinc. 

Combine  the  weight  of  ferric  oxide  found  here,  with  that 
found  in  the  purification  of  the  stannic  oxide,  and  calcu- 
late to  metallic  iron. 

The  analysis  may  be  made  in  another  way.  Determine 
the  tin  and  lead,  as  above,  in  the  filtrate,  precipitate  the 
copper  as  sulphide,  and  determine  it  as  cupreous  sulphide. 
(See  analysis  of  copper  ore.)  Then  oxidize  the  sulphur 
in  the  solution,  by  boiling  with  potassium  chlorate,  and 
determine  the  zinc  and  iron  as  above. 


CHAPTER    XXV. 

ARSENIC   ORE. 

Introduce  1  gm.  of  the  finely  pulverized  ore,  into  a  large, 
covered  porcelain  crucible,  add  15  c.  c.  of  strong  nitric- 
acid,  and  evaporate  to  pasty  condition ;  then  add  3  or  4 
gms.  of  dry  sodium  carbonate,  and  as  much  sodium  nitrate  ; 
heat  cautiously  to  perfect  dryness,  and  fuse  until  the  con- 
tents of  the  crucible  are  fluid.  Then  cool,  place  the  cru- 
cible and  contents  in  a  casserole,  containing  about  200  c.  c. 
of  water,  and  heat  until  the  mass  is  disintegrated  so  far  as 
to  leave  the  crucible.  Then  remove  the  crucible,  wash  it, 
adding  the  washings  to  the  fluid  in  the  casserole,  boil  until 
the  mass  in  the  casserole  becomes  pulverulent,  and  the 
fluid  concentrated  to  150  c.  c.  Cool,  add  50  c.  c.  of  alcohol 
stir  well,  filter,  wash  with  40  or  50  c.  c.  of  dilute  alcohol, 
(containing  1  volume  of  alcohol,  and  2  volumes  of  water). 
It  is  advisable  to  dry  the  residue,  and  repeat  the  fusion 
and  other  treatment,  described  above.  Combine  the  solu- 
tions which  will  contain  the  arsenic,  in  the  form  of  sodium 
arsenate,  and  also,  perhaps,  a  little  silica  and  alumina. 
Boil  out  the  alcohol,  keeping  up  the  volume  of  fluid  by 
occasionally  adding  water,  and,  after  removing  the 
alcohol,  acidulate  with  nitric  acid ;  add,  50  c.  c.  of  the 
ordinary  solution  of  ammonium  molybdate,  and  warm  for 
several  hours,  to  precipitate  the  arsenio-molybdate.  After 
the  precipitate  has  entirely  settled,  filter,  and  wash  with 
the  precipitant ;  dilute  with  an  equal  volume  of  water,  as 
in  the  determination  of  phosphoric  acid.  Dissolve  the 
precipitate  through  the  filter  with  dilute  ammonia,  wash 
the  filter  well  with  the  same,  and  allow  the  solution  tc 
stand  12  hours,  when  any  silico-molybdate  present  will  be 
decomposed,  and  the  silica  separate.  Filter  out  the  raili  ca 
wash  with  water,  and  acidify  the  filtrate  with  nitric  ac  id 


150  ARSENIC   ORE. 

The  arsenio-molybdate  will  be  precipitated,  and  the 
alumina  remain  in  solution.  Filter,  wash  with  30  or  40 
c.  c.  of  diluted  ammonium  molybdate  solution,  dissolve 
through  the  filter  with  ammonia  diluted  with  an  equal 
volume  of  water,  wash  with  the  same,  and,  to  the  filtrate, 
add  4  or  5  c.  c.  of  " magnesium  mixture,"  and  allow  it  to 
stand  for  12  hours.  After  the  precipitate  has  settled,  test 
as  to  whether  or  not  a  sufficient  amount  of  the  precipitant 
has  been  used,  by  mixing  a  few  drops  of  the  clear  fluid 
with  a  little  sodium  phosphate.  If  no  precipitate  appear, 
which  is  very  improbable,  add  more  u  magnesium  mix- 
ture," and  allow  the  whole  to  stand  until  the  magnesium 
arsenate  has  had  time  to  form  and  settle  completely ; 
then  filter,  and  wash  with  dilute  ammonia,  containing  one 
third  its  volume  of  alcohol.  Dissolve  the  precipitate 
through  the  filter  into  a  small  beaker  with  dilute  hydro- 
chloric acid,  add  slight  excess  of  ammonia,  and  alcohol  to 
the  amount  of  one  third  the  volume  of  the  solution,  and 
allow  all. to  stand  for  several  hours.  Then  filter,  wash 
with  dilute  ammonia  containing  alcohol,  dissolve  the  moist 
precipitate  through  the  filter  with  dilute  nitric  acid,  into  a 
small  porcelain  dish,  or  large  porcelain  crucible,  previously 
weighed ;  evaporate  to  dryness,  ignite  gently  at  first,  and 
then  strongly,  over  a  good  Bunsen  burner,  and  weigh  the 
magnesium  pyro-arsenate.  (See  Jour.  London  Chem.  Soc, 
August,  1877,  p.  222;  taken  from  Zeit.  f%  Anal.  Chem., 
XIV.,  356.)  The  results  are  accurate.  By  the  ordinary 
method  of  drying  the  precipitate  of  magnesium  arsenate, 
on  a  weighed  filter  at  100°  or  105°  C,  not  only  water  is  ex- 
pelled, but  also  ammonia.  (See  a  paper  by  Maclvor,  in 
Chem.  JVews,  Dec.  17,  1875.)  The  author's  experience 
confirms  Maclvor' s  conclusion. 

After  weighing  the  magnesium  pyro-arsenate,  in  order 
to  test  it  for  phosphoric  acid,  dissolve  it  in  hydrochloric 
acid,  add  sodium  sulphite,  saturate  with  sulphuretted 
hydrogen,  filter  out  the  arsenious  sulphide,  wash  well,  add 
to  the  filtrate  large  excess  of  nitric  acid,  boil  down  to  small 


ARSENIC.  151 

volume  (repeating  the  addition  of  nitric  acid  and  boiling, 
if  necessary),  until  the  sulphur  is  all  oxidized,  and  hydro- 
chloric acid  expelled.  Then  add  10  or  15  c.  c.  of  am- 
monium molybdate  solution.  Should  a  precipitate  of 
phospho-molybdate  occur,  determine  the  corresponding 
magnesium  pyro-phosphate,  and  deduct  it  from  the  mag- 
nesium pyro-arsenate  weighed  before,  and  calculate  the 
arsenic. 

Where  absolute  accuracy  is  not  required,  the  analysis 
may  be  made  more  expeditiously  by  treating  the  ore  with 
strong  nitric  acid,  adding  sodium  carbonate  and  sodium 
nitrate,  evaporating,  and  fusing  in  a  platinum  crucible, 
removing  the  heat  as  soon  as  the  flux  is  fluid,  and  then  di- 
gesting with  hot  water  until  the  mass  is  pulverulent.  By 
this  means,  the  arsenic  is  dissolved  as  sodium  arsenate, 
and  can  be  filtered  nearly  pure.  " Magnesium  mixture" 
is  now  to  be  added  to  the  solution  directly,  and  the 
analysis  conducted  as  above. 

To  insure  the  purity  of  the  precipitate,  it  is  well  to  dis- 
solve it  in  nitric  acid,  filter  out  any  insoluble  residue, 
which  is  to  be  deducted,  and  also  to  test  for  phosphoric 
acid,  which,  if  found,  is  also  to  be  deducted. 


Note. — Where  the  percentage  of  arsenic  in  the  ore  will  probably  amount  to  20 
or  25  per  cent.,  it  is  usually  advisable  when  the  molybdate  separation  is  used,  to 
make  the  solution  from  1  gm.  up  to  some  convenient  bulk,  and  to  take  some 
fraction,  as  one-half  or  one-quarter,  for  the  determination. 


CHAPTER  XXVI. 

ANTIMONY   ORE. 

To  determine  the  antimony,  add,  to  1  gm.  of  the  finely 
pulverized  ore,  5  c.  c.  of  concentrated  nitric  acid,  10  c.  c, 
of  concentrated  hydrochloric  acid,  3  gms.  of  tartaric  acid,, 
and  heat  on  a  water-bath  until  the  substance  is  nearly  dry 
in  order  to  expel  most  of  the  free  acid.  Then  dilute  with 
100  c.  c.  of  water,  make  alkaline  with  ammonia,  add  8 
or  10  c.  c.  of  yellow  ammonium  sulphide,  and  warm 
gently  for  an  hour.  Enough  of  the  alkaline  sulphide 
should  be  added  to  make  the  fluid  yellow.  Filter 
and  wash  with  hot  water  until  the  washings  run 
through  the  filter  perfectly  colorless.  The  filtrate  will 
contain  the  antimony  as  ammonium  sulph-antimonate. 
Acidulate  the  filtrate  with  hydrochloric  acid,  and  allow 
the  precipitate  of  antimony  sulphide  to  settle  completely. 
Dry  the  residue  remaining  upon  the  filter,  fuse  it  with  4 
or  5  gms.  of  sodium  carbonate,  and  1  gm.  of  sodium  nitrate, 
treat  the  fused  mass  with  an  excess  of  hydrochloric  acid 
and  about  1  gm.  of  tartaric  acid,  evaporate  off  excess  of 
acid  as  above,  add  25  c.  c.  of  water,  make  alkaline  with 
ammonia,  treat  with  yellow  ammonium  sulphide,  filter, 
wash,  acidulate  the  filtrate  with  hydrochloric  acid,  and, 
should  any  antimony  sulphide  be  precipitated,  allow  it  to 
settle  as  directed  before.  Filter  out  the  precipitates  of  an- 
timony sulphide  on  the  same  filter,  wash  with  hot  water, 
then  with  alcohol  to  displace  the  water  adhering  to  the 
precipitate,  dry  it  at  a  low  heat,  wash  with  carbon  disul- 
phide,  to  dissolve  the  free  sulphur,  and  dry  at  a  tempera- 
ture not  over  100°  C.  The  heat  should  be  moderate,  and 
continued  no  longer  than  is  necessary.  When  the  precip- 
itate is  dry  enough  to  be  removed  from  the  filter,  brush  it 
into  a  clock-glass,  cleaning  the  paper  as  thoroughly  as  pos- 


ANTIMONY.  158 

sible,  and  place  the  filter  in  a  capacious  weighed  porcelain 
crucible,  furnished  with  a  cover.  Moisten  it  with  ordinary 
concentrated  nitric  acid,  add  4  or  5  c.  c.  of  red  fuming  nitric 
acid,  and  evaporate  on  a  water-bath  to  dryness.  Then 
transfer  the  precipitate  to  the  crucible,  add  a  little  concen- 
trated nitric  acid  cautiously  by  means  of  a  pipette,  insert- 
ing the  point  of  the  pipette  under  the  edge  of  the  lid. 
When  the  violent  action  is  over,  add  also  to  the  precipi- 
tate 8  or  10  times  its  volume  of  red  fuming  nitric  acid,  ob- 
serving the  same  precautions  as  before,  and  evaporate  to 
dryness  on  a  water-bath,  having  removed  the  cover  from 
the  crucible  as  soon  as  all  danger  of  loss  by  spirting  is  past. 
Finally,  ignite  cautiously  over  a  Bunsen  burner,  to  expel 
the  sulphuric  acid,  and  convert  the  precipitate  into  anti- 
mony tetroxide  (Sb304),  from  which  calculate  the  anti- 
mony. This  method  is  due  to  Bunsen.  (See  Fres.,  Quant. 
Anal.,  §  125,  2,  b,  p.  243.)  All  the  filtrates  should  be 
treated  again  with  sulphuretted  hydrogen,  to  recover  any 
possible  traces  of  antimony  which  may  have  escaped  pre- 
cipitation before. 


CHAPTER    XXVII. 

TYPE   METAL. 

The  metals  to  be  looked  for  are  antimony,  lead,  tin, 
and  iron.     In  rare  cases,  a  little  arsenic  may  be  present. 

To  1  gm.  of  the  metal,  comminnted,  by  drilling,  shav- 
ing, or  filing,  add  3  or  4  gms.  of  tartaric  acid,  and  20  c.  c. 
of  dilute  nitric  acid,  prepared  by  mixing  1  part  of  con- 
centrated nitric  acid  with  2  parts  of  water.  Digest  on  a 
water-bath  until  excess  of  nitric  acid  is  entirely  expelled, 
add  50  c.  c.  of  water,  excess  of  ammonia,  10  c.  c.  of 
yellow  ammonium  sulphide,  and  allow  to  stand  on  a 
water-bath  for  3  or  4  hours,  the  water  in  the  bath  being 
heated  to  a  point  just  below  boiling.  Do  not  heat  strong- 
ly. Dilute  to  about  100  c.  c,  filter,  and  wash  with  water 
until  the  washings  are  colorless.  The  oxides  of  antimony 
*and  tin  go  into  solution  as  ammonium  sulphantimonate 
and  sulpho-stannate,  while  the  lead  and  iron  sulphides 
remain  on  the  filter  undissolved.  Wash  the  contents 
of  the  filter,  dry  the  filter,  burn  it  in  a  porcelain  crucible, 
after  moistening  with  nitric  acid,  add  to  the  ash  5  or  6 
drops  of  nitric  acid,  warm,  and  wash  it  into  the  casserole. 
Then  add  6  or  7  c.  c.  of  nitric  acid  and  2  or  3  c.  c.  of  sul- 
phuric acid,  and  heat  until  fumes  of  S03  appear ;  cool, 
add  50  c,  c.  of  water,  filter,  and  wash  with  40  or  50  c.  c.  of 
water  containing  1  per  cent  of  sulphuric  acid.  Dry  the 
filter  and  contents,  transfer  the  latter  to  a  clock-glass, 
place  the  filter  in  a  capacious  weighed  porcelain  crucible, 
add  8  or  10  drops  of  nitric  acid  and  4  or  5  drops  of  sul- 
phuric acid,  evaporate  off  the  excess  of  acid,  and  ignite. 
Again  add  4  or  5  drops  of  nitric  acid  and  1  or  2  drops  of 
sulphuric  acid,  expel  excess  of  acid,  transfer  the  contents 
of  the  filter  from  the  clock-glass  to  the  crucible,  ignite  all, 


ANTIMONY.  155 

cool,  weigh  the  lead  sulphate,  and  calculate  the  per  cent 
of  lead.     (Consult  analysis  of  galena. ) 

Acidify  the  alkaline  filtrate  containing  the  tin  and  anti- 
mony, and  perhaps  some  arsenic,  with  hydrochloric  acid, 
und  allow  the  sulphides  to  settle  in  a  warm  place,  avoid- 
ing great  heat.  Then  filter,  wash  with  water,  displace  the 
water  with  a  little  alcohol,  dry  at  a  moderate  heat,  run  a 
little  carbon  disnlphide  through  the  filter,  to  dissolve  out 
free  sulphur,  expel  excess  of  carbon  disnlphide  at  gentle 
heat  (better  in  a  steam-bath),  place  the  filter  and  contents 
in  a  large  porcelain  crucible,  add  1  or  2  c.  c.  of  nitric  acid, 
and  cover  with  a  glass.  When  the  violent  action  is  over, 
add  4  or  5  c.  c.  of  red  fuming  nitric  acid,  and  evaporate  at 
a  gentle  heat  nearly  to  dryness  to  convert  the  sulphides 
into  oxides.  Then  neutralize  the  remaining  acid  with 
pure  sodium  hydrate,  wash  the  oxides  into  a  silver  dish 
with  water  containing  a  little  sodium  hydrate  (using  as 
little  as  possible),  evaporate  nearly  to  dryness,  add  about 
8  parts  of  pure  sodium  hydrate,  and  a  little  sodium  ni- 
trate, continue  the  evaporation  to  perfect  dryness,  and  fuse. 
As  soon  as  the  mass  is  fused,  remove  the  heat,  and  when  it 
is  cool  enough  add  100  c.  c.  of  hot  water,  and  boil  until 
the  contents  of  the  dish  are  pulverulent.  Finally,  cool, 
add  alcohol  to  the  amount  of  one  third  the  volume  of  the 
fluid,  filter,  wash  the  residue  with  dilute  alcohol  (prepared 
by  mixing  1  part  of  alcohol  with  2  parts  of  water),  to 
which  has  been  added  a  few  drops  of  strong  solution  of 
sodium  carbonate.  The  insoluble  sodium  antimonate  will 
remain  on  the  filter,  while  the  sodium  stannate  and 
sodium  arsenate  go  into  solution.  Wash  the  antimonate 
from  the  filter  into  a  beaker  with  water,  place  the  beaker 
under  the  filter,  and  pour  through  the  latter  10  or  15  c.  c. 
of  warm  concentrated  hydrochloric  acid,  containing  1  gm. 
of  tartaric  acid,  wash  with  a  little  water,  and  warm  until 
everything  is  dissolved.  Dilute  the  solution  to  100  c.  c, 
saturate  it  with  sulphuretted  hydrogen,  filter,  wash,  treat 
the  precipitate  as  directed  in  the  analysis  of  antimony  ore, 


156  TYPE   METAL. 

and  calculate  the  per 'cent  of    antimony.      (See    Fres., 
Quant.  Anal.,  %  165 — 4— a,  p.  398.) 

Should  there  be  no  arsenic  present,  acidify  the  nitrate 
containing  tin  with  hydrochloric  acid,  and  saturate  with 
sulphuretted  hydrogen.  Heat,  filter,  wash  with  solution 
of  ammonium  acetate,  containing  a  little  free  acetic  acid, 
dry,  roast  at  gentle  heat  in  a  weighed  porcelain  crucible, 
then  heat  strongly,  cool,  weigh  the  stannic  oxide,  and  cal- 
culate the  per  cent  of  tin.  (See  analysis  of  tin  ore. )  Puri- 
fy the  weighed  precipitate  as  in  analysis  of  bronze.  Should 
arsenic  be  present,  it  will  be  found,  together  with  the  tin, 
in  the  filtrate  from  the  sodium  antimonate,  after  the  fusion 
with  sodium  hydrate.  Add  to  the  filtrate  1  or  2  c.  c.  of 
ammonia,  and  2  or  3  c.  c.  of  yellow  ammonium  sulphide, 
and  warm  gently  for  a  short  time.  Then  add  5  c.  c.  of 
" magnesium  mixture,"  and  allow  to  stand  for  12  hours. 
Filter  out  the  magnesium-ammonium  arsenate,  treat  it 
as  directed  in  the  analysis  of  arsenic  ore,  and  calculate 
the  per  cent  of  arsenic. 

Acidify  the  filtrate  from  the  magnesium  arsenate  with 
hydrochloric  acid,  precipitate  the  tin  as  sulphide,  and  pro- 
ceed to  determine  it  as  directed  above. 

The  filtrate  from  the  lead  sulphate  will  contain  the  iron. 
Precipitate  the  iron  as  basic  acetate,  filter,  wash  moder- 
ately, dissolve  the  precipitate  in  hydrochloric  acid,  re-pre- 
cipitate with  ammonia,  filter,  wash,  dry,  ignite,  weigh  the 
ferric  oxide,  and  calculate  the  per  cent  of  iron. 

Examine  the  filtrate  for  other  metals  of  Group  IV., 
and,  if  found,  determine  them.  (H.  Will,  Anleitung  f. 
Anal  Chem.,  225,  Ed.  1857.) 


CHAPTER    XXVIII. 


REFINED   LEAD. 


Determine  silver  in  separate  portion.     Note  1. 
For  other  metals,  dissolve  200  gms.  in  nitric  acid. 


Note  % 


Residue  (a). 
Sb,S:n.      Add   to  pre- 
cipitate  (r).    Note  2. 


Solution  (a). 
Add  sulphuric  acid.     Note  3. 


Residue  (b). 
PbS04.    Noted. 


Solution  (b). 
Evaporate.     Note  3. 


Precipitate  (c). 
PbS04.    Note  4. 


Filtrate  (d). 

Reject. 
Note  4. 


Free.  (d). 

Add    to 

Precipitate 

(/).    Note  4. 


Precipitate  (g). 
Fe,Zn,Co,Ni.     Note  7. 


Jtesidue  (h). 

Co,Ni. 
Notel. 


Prec.  (i). 
Fe.    Note  8. 


Solution  (j). 
Note  9. 


Solution  (h). 

Fe.Zn. 
Note  8. 

Solution  (i). 
Note  9. 

Prec.  (j). 
JVofe  9. 


Precipitate  (o). 
Cd.    iVbfe  11. 


Solution  (x). 
Note  11. 


Solution  (c). 
Dilute  and  pass  H2S.     iVbte  5. 

Solution  (/).  Precipitate  (/). 

Evaporate  to  500  c.  c 
iVbfe  6. 


Solution  (g). 


Prec.  (Jc). 

Add  to 

precipitate 

(g).    NoteG. 


Solution  (k). 

Reject. 
Note  6. 


Solution  (m). 
iVbfe  11. 


Solution  (n) 

Cd,  etc. 
Note  11. 

Filtrate  (o). 

Note  11 


Prec.  (n). 
Bi.    iVb*e 
11. 


Precipitate  (x). 
Note  11. 


Sb,As,Sn,Bi,Cu,Cd, 
Pb.   Add  precipitate  (d). 
Note  10. 


Residue  (l). 

Bi,Cu,Cd, 
Pb.  Note  10. 
Prec.  (m). 

Reject. 
Note  10. 


Solution  (s). 

As,Sb,Sn. 
Note  12. 

Prec.  (*). 

As,Sb,Sn. 
Note  12. 


Solution  (I). 
As,Sb,Sn. 
Note  10. 


Note 
10. 


P.  (r.) 

Sb, 

As,Sn 

iV.  12. 


Residue  (s). 
Note  12. 


Filtrate  (t). 

Reject. 
!iVb*el2. 


As. 


Solution  (u). 
Note  12. 


Sb,Sn. 


Residue  (u). 
Notes  13  and  14. 


Compare  Fres.,  Zeit.  fur  An.  Chem.,  Yol.  VIII. ,  1869. 
The  lead  may  contain  silver,  copper,  bismuth,  cadmium, 
zinc,  iron,  nickel,  cobalt,  arsenic,  antimony,  tin,  manga- 
nese. 

Note  1. — The  silver  may  be  determined  either  by  cupel- 
lation,  or  by  a  wet  method.  If  the  latter  plan  is  adopted, 
weigh  200  gms.  of  pieces,  scraped  clean,  introduce  them 


158  REFINED   LEAD. 

into  a  i. 5-litre  flask,  add  nitric  acid  of  1.2  sp.  gr.,  in  small 
portions  at  a  time,  always  keeping  the  metal  in  excess, 
and  heat  the  liquid  nntil  only  about  5  or  10  gms.  of  lead 
remain  undissolved,  and  the  solution  begins  to  turn  yellow 
in  consequence  of  the  formation  of  lead  nitrite.  The  silver 
will  be  concentrated  in  the  residual  metal.  Withdraw  it 
from  the  solution,  and  dissolve  it  in  nitric  acid,  dilute  to 
200  c.  c.j  and  add  a  mixture  of  1  c.  c.  of  hydrochloric  acid 
and  50  c.  c.  of  water.  Allow  the  whole  to  stand  2  or  3 
days,  and  after  all  the  silver  chloride  has  settled,  draw  off 
the  clear  fluid,  and  filter  out  the  silver  chloride,  on  a  small 
filter,  wash  with  hot  water,  dry,  and  ignite  filter  and  pre- 
cipitate together  in  a  small  weighed  porcelain  crucible.  If 
the  amount  of  silver  chloride  is  so  considerable  that  there 
is  a  possibility  of  its  being  incompletely  reduced  by  the 
combustion  of  the  filter-paper,  the  residue  must  be  heated 
for  a  few  minutes  in  a  stream  of  hydrogen  before  weigh- 
ing. The  amount  left,  after  subtracting  the  filter-ash, 
gives  the  quantity  of  silver  in  the  200  gms.  of  lead.  The 
refined  metal  seldom  contains  more  than  0.0015  per  cent 
of  silver. 

Instead  of  treating  the  ignited  precipitate  with  hy- 
drogen, add  about  0.5  c.  c.  of  nitric  acid,  evaporate  to 
dryness,  again  add  0.5  c.  c.  of  nitric  acid,  heat  to  dissolve 
any  reduced  silver,  add  8  or  10  drops  of  hydrochloric  acid, 
evaporate  to  dryness,  fuse  the  silver  chloride,  cool,  weigh, 
and  calculate  the  silver.     (See  analysis  of  barium  chloride. ) 

Note1'!. — For  the  main  analysis,  weigh  200  gms.  of  lead, 
cleaned  as  before,  introduce  it  into  a  2-litre  flask,  add  500 
c.  c.  pure  nitric  acid  of  1.2  sp.  gr.  and  1  litre  of  water,  and 
allow  it  to  stand  for  24  hours.  Should  a  residue  (a)  con- 
taining antimony  and  tin  remain,  filter  it  out,  dissolve  it 
in  hydrochloric  acid,  dilute  a  little,  pass  sulphuretted 
hydrogen  through  the  solution,  filter  out  the  precipitate, 
wash,  and  reserve  it  to  go  with  precipitate  (r),  consisting  of 
the  sulphides  of  antimony,  arsenic,  and  tin. 

Note  3. — Transfer  the  clear  solution  (a)  to  the  2-litre  flask. 


ANTIMONY — METALS   OF  GEOUPS   IV.    AND  V.  159 

if  not  already  there,  add  65  c.  c.  of  pure  concentrated  sul- 
phuric acid,  shake,  cool,  fill  up  to  the  2-litre  mark,  agitate 
again,  and  allow  to  settle.  Then  siphon  off  accurately 
1750  c.  c.  of  the  clear  solution,  and  reject  the  rest  contain- 
ing lead  sulphate  or  residue  (b).  It  has  been  found,  by 
repeated  experiments,  that  the  lead  sulphate  from  200 
gms.  of  lead  occupies  44.99  c.  c,  or,  in  round  numbers,  45 
c.  c.  The  2-iitre  flask,  when  filled  to  the  mark,  will  hold, 
then  1955  a  c.  of  solution  and  45  c.  c.  of  lead  sulphate. 
But  as  1955  c.  c.  of  the  solution  correspond  to  200  gms.  of 
the  lead,  then  1750  c.  c.  of  solution  will  correspond  to 
179.03  gms.  of  the  original  lead,  or,  in  round  numbers,  179 
gms.  Consequently,  all  the  calculations  must  be  based 
upon  this  as  the  quantity  taken  for  analysis.  Evaporate 
the  1750  c.  c,  or  solution  (&),  to  fumes  of  S03,  allow  to  cool, 
add  60  c.  c.  of  water,  filter  off  and  wash  precipitate  (c)  of 
lead  sulphate,  containing,  perhaps,  a  little  antimony. 

Note  4. — Dissolve  precipitate  (c)  in  hydrochloric  acid, 
add  10  volumes  of  sulphuretted  hydrogen  water,  warm, 
pass  sulphuretted  hydrogen  gas,  allow  the  precipitate  to 
settle,  filter,  wash,  spread  filter  in  a  porcelain  dish,  heat 
with  a  solution  of  yellow  sulphide  of  ammonium  or  potas- 
sium, to  which  a  little  pure  sulphur  has  been  added,  filter, 
wash,  acidify  the  filtrate  with  hydrochloric  acid,  allow  the 
precipitate  to  settle  at  a  gentle  heat,  filter,  and  wash. 

Keject  the  filtrate,  or  filtrate  (d),  and  add  the  precipitate, 
or  precipitate  (d\  to  precipitate  (/).  If  precipitate  id) 
contains  much  lead,  treat  it  again  with  ammonium  or  po- 
tassium sulphide,  as  before,  filter,  acidulate  with  hydro- 
chloric acid,  allow  the  antimony  sulphide  to  settle,  filter, 
and  add  the  pure  antimony  sulphide  to  precipitate  (f). 

Note  5. — Dilute  solution  (c),  the  filtrate  from  precipitate 
(c)  of  lead  sulphate,  to  200  c.  c,  heat  to  70°  C,  pass  the 
sulphuretted  hydrogen,  allow  to  stand  12  hours  over  a 
very  gentle  heat,  filter  through  a  small  filter,  and  wash 
with  hot  water.  There  will  be  a  solution  (/),  which  may 
contain  iron,  zinc,  cobalt,  nickel,  and  manganese,  and  a 


160  EEFINED   LEAD. 

precipitate  (/),  which  may  contain  antimony,  arsenic,  tin, 
bismuth,  copper,  cadmium,  and  lead. 

Note  6. — Evaporate  solution  (/)  to  a  volume  of  about  400 
c.  c,  transfer  to  a  half -litre  flask,  make  alkaline  with  am- 
monia, mix  with  freshly -prepared  ammonium  sulph-hy- 
drate,  fill  the  flask,  and  allow  to  stand  24  hours.  When 
the  precipitate  (g)  has  settled,  filter,  acidify  the  filtrate,  or 
solution  (g),  with  acetic  acid,  and  boil  to  recover  any 
nickel  which  may  have  been  retained  in  the  solution. 
Filter  out  precipitate  (7c)  of  nickel  sulphide,  and,  after 
washing  it  slightly  and  drying,  add  it  to  precipitate  (g), 
which  contains  the  principal  part  of  the  nickel,  and  reject 
the  filtrate,  or  solution  (Jc). 

Note  7. — Treat  precipitate  (g),  containing,  perhaps,  iron, 
zinc,  nickel,  cobalt,  and  manganese,  on  the  filter,  with  a 
mixture  of  1  part  of  hydrochloric  acid  of  sp.  gr.  1.12,  and 
6  parts  of  sulphuretted  hydrogen  water,  pouring  back  the 
filtrate  repeatedly  on  the  filter,  to  avoid  increasing  the  vol- 
ume of  fluid  unnecessarily.  Burn  the  filter  containing  resi- 
due (h),  after  drying,  together  with  the  filter,  containing  pre- 
cipitate (7c),  in  a  porcelain  crucible,  treat  with  nitro-hydro- 
chloric  acid,  concentrate  the  solution,  add  a  little  water, 
filter,  wash,  make  the  filtrate  alkaline  with  ammonia,  add 
a  few  drops  of  ammonium  carbonate,  filter  into  a  platinum 
dish,  treat  the  filtrate  with  a  few  drops  of  strong  solution 
of  potassium  hydrate,  and  heat  until  ammonia  is  entirely 
expelled.  Then  filter  off  the  slight  flocculent  precipitate, 
wash,  dry,  ignite,  and  weigh  the  nickel  oxide,  and  calcu- 
late metallic  nickel.  (See  analysis  of  nickel  ore.)  Test 
the  precipitate  with  the  blow-pipe  for  cobalt. 

Note  8. — Add  a  few  drops  of  nitric  acid  to  solution  (h\ 
containing  the  iron  and  zinc,  concentrate,  make  alkaline 
with  ammonia,  filter  off  the  ferric  hydrate,  or  precipitate 
(i),  dissolve  the  precipitate  with  a  few  drops  of  hydro- 
chloric acid,  again  precipitate  with  ammonia,  filter,  wash, 
dry,  ignite,  weigh  the  ferric  oxide,  and  calculate  metallic 
iron.     To  verify  the  results,  fuse  the  precipitate  with  acid 


ZINC — MANGANESE — GROUP  VI.  161 

sodium  sulphate,  dissolve  in  water,  reduce  with  zinc  and 
platinum,  and  determine  the  iron  with  a  dilute  solution  of 
potassium  permanganate.  (See  analysis  of  ammonia-iron- 
alum.) 

Note  9. — Mix  solution  (i),  or  the  filtrate  from  the  ferric 
hydrate,  with  a  little  ammonium  sulph-hydrate  in  a  small 
flask,  and  allow  to  stand  for  24  hours  in  a  warm  place. 
Filter  out  precipitate  (J),  wash  and  digest  on  the  filter  with 
dilute  acetic  acid,  to  dissolve  out  any  manganese  sul- 
phides. Dissolve  the  residue  of  zinc  sulphides  remaining 
on  the  filter  with  hydrochloric  acid,  boil,  after  adding  a 
little  potassium  chlorate  to  oxidize  the  sulphur,  precipi- 
tate the  zinc  with  sodium  carbonate,  and  from  the  ignited 
precipitate  calculate  the  zinc.     (See  analysis  of  zinc  ore.) 

Boil  solution  (J),  or  the  acetic  acid  solution  of  manganese 
sulphide,  to  small  volume,  add  a  little  bromine  water, 
warm  until  the  excess  of  bromine  is  expelled,  filter,  wash 
with  hot  water,  dry,  ignite  the  precipitate,  and  calculate 
the  manganese.     (See  analysis  of  manganese  ore.) 

Note  10. — Heat  precipitate  (f\  which  may  contain  anti- 
mony, arsenic,  tin,  copper,  bismuth,  cadmium,  and  lead, 
after  adding  precipitate  (/),  with  a  solution  of  potassium 
sulphide,  to  which  some  pure  sulphur  has  been  added, 
filter  out  residue  (?),  which  may  contain  bismuth,  copper, 
cadmium,  and  lead,  and  wash  with  hot  water.  Acidulate 
the  filtrate,  or  solution  (I),  which  may  contain  arsenic,  an- 
timony, and  tin,  with  hydrochloric  acid,  and  allow  the  pre- 
cipitate to  settle  completely.  Filter  out  precipitate  (r), 
which  may  contain  arsenic,  antimony,  and  tin,  and  reject 
the  filtrate,  or  solution  (r). 

I  Heat  residue  (Z),  (insoluble  in  potassium  sulphide)  nearly 
to  boiling,  in  a  porcelain  dish,  with  dilute  nitric  acid  (pre- 
pared by  mixing  1  part  of  acid  of  1.2  sp.  gr.  with  12  parts 
of  water).  When  the  precipitate  is  dissolved,  filter,  wash 
the  paper  slightly,  dry,  ignite  it,  and  add  the  ash  to  the 
nitric-acid  solution.  Then  add  2  c.  c.  of  dilute  sulphuric 
acid,  evaporate  to  fumes  of  S03,  dilute  a  little,  and  filter 


162  KEFINED   LEAD. 

out  and  wash  precipitate  (m)  of  lead  sulphate,  which  may 
be  rejected.     (See  analysis  of  galena.) 

JVote  11. — Nearly  neutralize  solution  (m)  (or  the  filtrate 
from  the  lead  sulphate,  and  which  may  contain  bismuth, 
copper,  cadmium,  and  silver),  with  pure  potassium  hydrate, 
add  !N"a3C03  and  a  little  of  a  solution  of  pure  potassium  cy- 
anide free  from  potassium  sulphide,  and  heat  gently.  If 
a  precipitate  (n)  of  bismuth  hydrate  is  produced,  filter  it 
out,  wash,  dissolve  it  in  dilute  nitric  acid,  precipitate  it 
with  ammonium  carbonate,  weigh  it  as  bismuth  trioxide 
(Bi203),  and  calculate  the  metallic  bismuth.  (See  Fres., 
Quant.  Anal.  §  120.)  To  solution  (n)  add  a  little  more  po- 
tassium cyanide  and  a  few  drops  of  potassium  sulphide, 
filter  and  wash  the  precipitate  (o)  of  sulphides  of  cadmi- 
um and  silver,  dissolve  in  dilute  nitric  acid,  add  a  little 
hydrochloric  acid,  filter  out  and  wash  the  precipitate  of 
silver  chloride  or  precipitate  (x),  which  may  be  rejected, 
as  the  silver  is  determined  elsewhere.  Evaporate  solution 
x),  containing  cadmium,  nearly  to  dryness,  add  a  few 
drops  of  solution  of  sodium  carbonate,  filter  out  the  pre- 
cipitate of  cadmium  carbonate,  wash,  dry,  ignite,  and 
weigh  the  cadmium  oxide,  and  from  it  calculate  metallic 
cadmium.  To  prevent  reduction  and  volatilization  of  cad- 
mium during  the  ignition,  moisten  the  filter  with  solution 
of  ammonium  nitrate. 

If  no  precipitation  of  the  cadmium  is  produced  by  the  so- 
dium carbonate,  add  a  little  potassium  hydrate,  and  if  one 
then  forms,  filter,  wash,  and  proceed  as  above.  Mix  the 
filtrate  from  the  sulphides  of  silver  and  cadmium,  or  filtrate 
(o),  with  a  small  quantity  of  nitric  and  sulphuric  acids,  and 
evaporate  nearly  to  dryness.  Then  add  a  few  drops  of  hy- 
drochloric acid,  and  heat  until  cyanogen  is  expelled.  Fil- 
ter, if  necessary,  and  determine  the  copper  by  one  of  the 
methods  given  in  the  analysis  of  copper  ore. 

"When  cadmium  is  absent,  the  separation  of  the  bismuth 
and  copper  may  be  effected  by  means  of  ammonia  and  am- 
monium carbonate,  removing  any  silver  by  hydrochloric 


METALS   OF  GKOUP  VI.  16& 

acid  before  precipitating  copper  sulphide.  (For  precau- 
tions to  be  observed,  see  Fres.,  Quant.  Anal.,  §  163,  5.) 

Note  12.  —To  precipitate  (r),  which  may  contain  arsenic, 
antimony,  and  tin,  and  which  was  obtained  by  acidifying 
the  potassium  sulphide  solution  (T)  with  hydrochloric 
acid,  add  the  sulphuretted  hydrogen  precipitate  from  the 
solution  of  residue  (a),  (see  Note  2),  dry,  and  treat  repeat- 
edly with  carbon  disulphide.  After  the  carbon  disulphide 
has  evaporated  from  the  filter,  warm  it,  with  its  contents,  in 
a  covered  porcelain  crucible,  after  adding  a  few  drops  of 
red  fuming  nitric  acid,  heat  the  solution  cautiously  to  expel 
excess  of  nitric  acid,  add  sodium  carbonate  in  excess  and  a 
little  sodium  nitrate,  evaporate  to  dryness,  and  heat  until 
the  mass  melts,  and  becomes  white.  Transfer  the  fused 
mass  to  a  small  mortar,  add  a  little  water,  and  pulverize 
carefully.  Then  wash  it  into  a  breaker,  and  proceed  as  di- 
rected in  the  analysis  of  type  metal.  (See  also  Fres., 
Quant.  Anal.,  page  427.) 

Dissolve  residue  is)  of  sodium  antimonate,  in  hydro- 
chloric and  tartaric  acids,  pass  sulphuretted  hydrogen,  set 
aside  for  a  few  hours,  filter  out  antimony  sulphide,  wash, 
dry  the  precipitate,  and  reserve  it  to  be  combined  with, 
the  sulphuretted  hydrogen  precipitate  from  the  solution 
of  residue  (u). 

Evaporate  solution  (s),  which  may  contain  arsenic,  anti- 
mony, and  tin,  in  order  to  expel  alcohol,  add  excess  of  di- 
lute sulphuric  acid,  evaporate  to  expel  nitric  acid,  add 
water,  heat  to  70°  C,  and  pass  sulphuretted  hydrogen. 
When  precipitate  {t)  has  settled,  filter,  and  wash  with 
water,  and  reject  the  filtrate,  or  solution  (t).  If  no  tin  be 
present,  treat  precipitate  (t),  on  the  filter,  with  a  cold  con- 
centrated solution  of  ammonium  carbonate,  pouring  the 
filtrate  back  on  the  filter  repeatedly  in  order  to  avoid  the 
use  of  a  large  excess  of  solution  of  ammonium  carbonate. 
The  ammonium  carbonate  solution  (u)  will  contain  the 
arsenic.  Acidulate  it  with  hydrochloric  acid,  add  a  little 
filtered    sulphuretted    hydrogen  water,   filter  through  a 


164  REFINED   LEAD. 

small  tube,  in  which  a  little  asbestos  has  been  placed, 
both  having  been  previously  heated  and  weighed.  When 
the  whole  of  the  precipitate  has  been  transferred  to  the 
little  tube,  heat  it  at  100°  C,  until  the  greater  portion  of 
the  water  is  expelled,  and  then  heat  it  gently,  not  much 
above  100°  C,  in  a  stream  of  dried  carbon  dioxide, 
allow  it  to  cool  in  a  current  of  the  gas,  displace  the 
carbon  dioxide  with  atmospheric  air,  and  weigh  the  tube 
and  contents,  and,  from  the  trisulphide,  calculate  the 
arsenic.  A  better  plan  is  to  filter  out  the  arsenious  sul- 
phide on  a  very  small  filter,  oxidize  the  filter  and  sul- 
phide together  by  evaporation  with  fuming  nitric  acid, 
fuse  the  residue  in  platinum  with  a  little  sodium  carbon- 
ate and  nitrate,  dissolve  in  water,  and  weigh  the  arsenic 
as  magnesium  pyro-arsenate,  as  directed  in  the  analysis  of 
arsenic  ore. 

Note  13. — Dissolve  residue  (u)  containing  antimony,  to- 
gether with  the  precipitate  from  solution  of  residue  (s),  in 
strong  hydrochloric  acid,  pass  sulphuretted  hydrogen, 
filter  through  a  small  tube  in  the  same  way  as  directed 
above  in  the  case  of  arsenic,  heat  gently  in  a  stream  of 
dried  carbon  dioxide,  until  the  antimony  trisulphide  turns 
black,  cool  in  a  current  of  the  gas,  displace  the  latter  by  a 
current  of  dry  air,  weigh  the  tube  and  contents,  and  cal- 
culate the  antimony.  Or,  oxidize  the  antimony  oxide 
by  Bunsen's  method  with  nitric  acid,  and  weigh  it,  as 
directed  in  the  analysis  of  antimony  ore,  as  antimony 
tetroxide. 

Note  14. — If  tin  be  present,  after  expelling  alcohol, 
passing  sulphuretted  hydrogen,  and  filtering  out  the  pre- 
cipitate, dissolve  the  latter  in  potassium  sulphide,  add  ex- 
cess of  sulphurous  acid,  digest  for  some  time  on  a  water- 
bath,  and  then  boil  until  two  thirds  of  the  water,  and  all 
the  sulphurous  acid  are  expelled.  Solution  if)  will  con- 
tain all  the  arsenic.  (See  Bunsen,  in  Annal.  d.  CJiem.  u. 
Pharm.,  106,  3,  and  Fres.,  Quant.  Anal.,  §165-6.) 

Precipitate  the  arsenic  as  sulphide,  oxidize,  fuse,  take 


TIN — SULPHUK.  165 

up  with  water,  and  weigh  the  arsenic  as  magnesium  pyro- 
arsenate,  as  directed  in  the  analysis  of  arsenic  ore. 

Residue  (t)  will  contain  the  tin  and  antimony.  Oxidize 
it  with  fuming  nitric  acid  in  a  weighed  porcelain  crucible, 
and  weigh.  Then  ignite  in  a  stream  of  hydrogen  to  expel 
the  antimony  tetroxide,  oxidize  again  with  nitric  acid,  and 
weigh  the  stannic  oxide,  from  which  calculate  the  tin. 
Calculate  the  antimony  from  the  loss  of  antimony  tetrox- 
ide. The  tin  and  antimony  may  be  separated  and  de- 
termined by  oxidizing  the  residue  left  after  extracting  the 
arsenic,  with  nitric  acid,  fusing,  dissolving  in  water,  filter- 
ing out  the  soluble  stannate  from  the  insoluble  antimon- 
ate,  which  latter  is  to  be  dissolved  in  hydrochloric  and  tar- 
taric acids,  precipitated  as  sulphide,  and  the  sulphide 
oxidized  and  weighed  as  antimony  tetroxide,  as  directed 
in  the  analysis  of  antimony  ore. 

To  determine  the  tiu3  precipitate  the  sulphide  from  the 
solution  of  stannate,  by  means  of  sulphuretted  hydrogen, 
filter  it  out,  and  burn  it  to  stannic  oxide,  as  directed  in 
the  analysis  of  tin  ore. 

Note  15. — To  determine  the  small  quantity  of  sulphur 
which  may  be  present  in  the  lead,  draw  out  a  piece  of 
combustion  tubing  about  1  metre  long,  and  of  about  2 
centimetres  diameter,  to  a  long  point,  which  is  bent  down 
so  as  to  dip  into  a  small  3-bulbed  U  tube  filled  with  water. 
Also  narrow  the  combustion  tube  in  the  middle,  so  as  to 
form  a  kind  of  bridge.  Introduce  into  the  anterior  end  of 
the  tube  about  100  gms.  of  the  lead,  in  the  form  of  a  rod 
of  about  1  centimetre  diameter,  close  the  tube  with  a  com- 
mon cork,  connect  it  with  a  smaller  tube  containing  frag- 
ments of  charcoal,  and  place  it  in  a  combustion  furnace. 
Then  heat  the  charcoal  to  the  point  of  ignition,  and  pass  a 
current  of  chlorine.  When  the  tubes  are  filled  with 
chlorine,  melt  the  lead  carefully,  the  tube  being  so  in- 
clined that  the  melted  lead  will  flow  against  the  bridge, 
but  not  over  it,  and  not  flow  back  against  the  cork.  Keep 
the  charcoal  red  hot  to  remove  any  oxygen  from  the 


166  EEFINED   LEAD. 

chlorine.  Regulate  the  heat  so  that  the  lead  will  burn 
slowly  to  lead  chloride,  and  collect  in  the  empty  part  of 
the  tube.  If  the  stream  of  chlorine  is  properly  regulated, 
and  the  lead  chloride  not  heated,  very  little  of  it  will  pass 
over  into  the  U  tube.  Wash  the  contents  of  the  U  tube 
into  a  beaker,  precipitate  the  S03  with  barium  chloride  as 
usual,  and  calculate  the  sulphur. 


CHAPTER    XXIX. 


WHITE   PAINT   GROUND   IN   OIL. 

Extract  the  oil.  Note  1.  The  dry  paint  may  contain 
BaS04,  PbS04,  CaS04,  2PbC03— PbH202,  BaC03,  CaC03,  ZnO, 
PbO,Si02,Al2,(Si03)3.     Note  2. 


Residue  (a). 
BaS04,PbS04,CaS04,Si02,Al2 


(Si03)3. 
Residue  (b). 
BaS04,PbC03, 
CaC03,Si02,Al2 
(Si03)3.    Note  4. 

Residue  (c). 
BaS04,Si02,Al2 
(SiOs)3.      Notes  5 
and  6. 

Precipitate  (d). 
PbS.     Note  7. 


Note  3. 

Filtrate  (b). 
(NH4)8S04.     I 
may  be  rejected 
Note  3. 


Solution  (c). 

Pb(C2H302)2, 
and  Ca(C8H802)8. 
Note  7. 

Solution  (d). 

Ca(C2H302)2. 
Note  8. 


Solution  (a). 

Pb(C8H302)2,Zn(C2H302)2,Ca(C3H, 

02)2,Ba(CsHs03)a.    iVb^e  9. 


Precipitate  (e). 
PbS,ZnS.    iVofe9. 


Res.  (/). 
PbS04. 

iVbfe  9. 


Filt.  (/). 
ZnS04. 
iVofe   10. 


Filtrate  (e). 
Ca(C2H302)2,Ba 
(C8H308)2.     Note 
11. 

Prec.  (g).  Filt.  (g). 
BaS04.  Ca(C2H8 
Note  11.       02)8. 
Note   12. 


The  paint  may  contain,  besides  the  oil,  one  or  more  of 
the  following  constituents,  namely  :  Sulphates  of  lead, 
barium,  and  calcium  ;  carbonates  of  lead,  barium,  and  cal- 
cium ;  oxides  of  lead  and  zinc,  and  also  silica  and  clay. 

Make  a  careful  qualitative  analysis  of  the  paint,  after 
extracting  the  oil,  for  upon  it  will  depend  the  character 
of  the  quantitative  analysis. 

Notel. — Weigh  a  clean  dry  flask,  which  holds  about 
150  c.  c.j  and  introduce  into  it  3  or  4  gms.  of  the  paint, 
and  note  the  weight.  Then  add  30  or  40  c.  c.  of  ether  or 
gasoline,  shake  well,  and  heat  over  steam  until  the  fluid 
boils.  Allow  the  solid  matter  to  settle,  and  decant  the 
clear  fluid  on  a  dny  filter  without  disturbing  the  residue 
more  than  is  necessary.  Repeat  the  operation  with  25  or 
30  c.  c.  of  the  solvent.     Finally,  wash  the  contents  of  the 


168  PAINT. 

flask  on  the  filter  with  25  or  30  c.  c.  of  ether  or  gasoline, 
and  dry  the  filter  and  contents,  in  an  air-bath,  at  100°  C. 
The  quantitative  analysis  may  be  made  of  a  portion  of 
this. 

To  determine  the  oil,  evaporate  the  filtrate  in  a  weighed 
dish,  without  application  of  heat,  until  only  oil  is  left, 
and  then  in  an  air-bath,  at  a  temperature  of  100°  C,  for 
about  an  hour,  cool,  and  weigh.  Should  there  be  any 
water  in  the  oil,  as  there  may  be,  if  the  ether  used  was  not 
perfectly  anhydrous,  continue  to  heat  at  100°  C.  until  it  is 
expelled,  and  then  cool  and  weigh.  Should  the  filtrate  be 
turbid,  and  not  cleared  by  refiltering,  as  is  sometimes  the 
case,  pour  it  into  a  measured  flask,  dilute  to  a  known 
volume,  dilute  with  ether  or  gasoline,  as  the  case  may  be, 
cork,  and  set  it  aside.  After  the  solid  matter  has  settled, 
take  an  aliquot  portion  of  the  clear  fluid,  evaporate  it  in  a 
weighed  dish,  as  directed  above,  and  calculate  the  per  cent 
of  oil.  The  proportion  of  solid  matter  will  be  too  small  to 
render  it  necessary  to  make  the  allowance  for  its  volume, 
as  in  the  case  of  refined  lead. 

Note  2. — Weigh  carefully  1  gm.  of  the  dry  residue, 
from  which  the  oil  has  been  thoroughly  extracted,  and 
dissolve  it  in  about  25  c.  c.  of  hot  acetic  acid,  in  a  covered 
vessel.     Filter,  and  wash  with  hot  water. 

If  there  be  any  residue  (a)  left  on  the  filter,  it  will  con- 
tain the  silica  and  clay,  and  sulphates  of  barium  calcium 
and  lead,  that  may  be  present  in  the  paint. 

Solution  (a)  may  contain  lead,  zinc,  calcium  and  barium 
in  the  form  of  acetates,  the  last  being  due  to  the  use  of 
witherite  (barium  carbonate). 

Note  3. — Treatment  of  residue  (a) : 

Wash  it  from  the  filter  into  a  beaker  with  water,  add  8 
or  10  gms.  of  ammonium  carbonate,  plug  the  point  of  the 
funnel,  and  fill  also  with  a  strong  solution  of  ammonium 
carbonate,  placing  it  in  a  filter-stand  over  the  beaker,  and 
allow  all  to  stand  for  12  hours,  with  frequent  stirring. 
By  this  means,  the  sulphates  of  lead  and  calcium  will  be 


BARYTES,    ETC.  169 

converted  into  carbonates,  while  the  barinm  sulphate, 
silica,  and  clay  will  remain  unaltered.  Then  remove  the 
plug  from  the  point  of  the  funnel,  allow  the  fluid  in  the 
filter  to  run  through  into  a  second  beaker,  pour  the  solu- 
tion of  ammonium  carbonate,  from  the  first  beaker,  on  the 
same  filter,  also  transfer  to  it  residue  (b)  (which  may  con- 
tain sulphate  of  barium,  carbonates  of  calcium  and  lead, 
and  silica  and  clay),  and  wash  well  with  hot  water.  The 
filtrate  and  washings,  or  filtrate  (b),  will  contain  the  sul- 
phuric acid,  which  was  combined  with  calcium  and  lead, 
and  may  be  rejected.  (See  note  on  galena  analysis,  p.  144.) 

Note  4. — Pour  through  the  filter  containing  residue  (b) 
(or  the  carbonates  of  calcium  and  lead,  the  sulphate  of 
barium,  and  the  silica  and  clay),  hot  acetic  acid  until  it 
produces  no  effervescence,  and  wash  well  with  water. 

Residue  (c)  will  contain  any  sulphate  of  barium,  silica, 
and  clay,  while  filtrate  (c)  will  contain  any  acetates  of  lead 
and  calcium. 

Note  5. — Dry,  ignite,  and  weigh  residue  (c).  Then  fuse 
it  with  sodium  carbonate,  boil  the  fused  mass  in  water, 
filter,  and  wash  out  alkaline  sulphate.  Treat  the  residue, 
containing  barium  carbonate,  with  hot  dilute  hydrochloric 
acid,  by  pouring  it  through  the  filter,  and  wash  the  latter 
well  with  hot  water,  allowing  the  filtrate  and  washings  to 
run  together  into  a  separate  beaker.  To  the  clear  acid  so 
lution  add  sulphuric  acid,  and  determine  the  barium  sul- 
phate as  usual.  This  will  give  the  amount  of  barytes  in 
the  paint.  The  difference  between  this  weight  and  that  of 
the  total  residue  (c)  will  give  the  amount  of  silica  and 
clay. 

Note  6. — Evaporate  nearly  to  dryness  the  filtrate  from 
the  barium  sulphate,  after  washing  into  it  any  residue 
left  upon  the  filter,  after  dissolving  the  barium  carbonate, 
transfer  to  a  platinum  crucible,  add  some  acid  sodium  sul- 
phate, and  fuse.  When  the  mass  is  cool  enough,  add  a 
little  sulphuric  acid,  heat  until  the  mass  is  brought  to  a 
pasty  consistence,  cool,  and  dissolve  in  water.     By  this 


170  PAINT. 

mea  ns,  the  silica  will  be  rendered  insoluble,  and  the  alumina 
dissolved.  Filter  out  and  weigh  the  silica ;  precipitate 
the  alumina  with  ammonia,  and  determine  it  as  usual. 
Calculate  the  alumina  to  clay  (Al2(Si03)3).  Any  excess  of 
silica  is  probably  due  to  the  use  of  infusorial  earth. 

Note  7. — Saturate  the  nitrate  from  the  barium  sulphate, 
clay,  and  silica,  or  acetic  acid  solution  (c),  with  sulphu- 
retted hydrogen,  filter  out  the  lead  sulphide,  or  precipi- 
tate (d),  and  wash  it  with  a  little  sulphuretted  hydrogen 
water.  Then  wash  the  precipitate  from  the  filter  into  a 
beaker,  dry  the  filter,  transfer  it  to  a  porcelain  crucible, 
moisten  it  with  nitric  acid,  burn  it,  add  the  ash  to  the 
precipitate,  and  dissolve  all  with  nitric  acid.  Then  add  a 
little  concentrated  sulphuric  acid,  evaporate  to  fumes  S03, 
dilute,  filter  out,  and  determine  the  lead  sulphate  existing 
as  such  in  the  paint.     (See  analysis  of  galena.) 

Note  8. — Boil  out  the  sulphuretted  hydrogen  from  the 
filtrate  from  the  lead  sulphide,  or  solution  (d),  which 
may  contain  calcium  acetate,  add  excess  of  ammonia 
and  ammonium  oxalate,  filter,  treat  the  precipitate  as 
directed  in  the  analysis  of  calcite,  and  weigh  the  calcium 
sulphate  which  existed  in  the  paint  as  such. 

Note  9. — Treatment  of  solution  (a) : 

Solution  (a)  may  contain  acetates  of  lead,  zinc,  calcium, 
and  barium.  Saturate  with  sulphuretted  hydrogen,  filter 
out,  and  wash  precipitate  (e),  which  may  contain  sulphides 
of  lead  and  zinc,  dissolve  the  precipitate  in  nitric  acid, 
add  sulphuric  acid  to  the  solution,  evaporate  to  fumes  of 
S03,  dilute,  filter  out  the  lead  sulphate,  or  residue  (/), 
observing  the  directions  given  in  the  analysis  of  galena, 
and  calculate  to  basic  carbonate  of  lead  (2PbC03,PbH202). 
(See  Note  13.) 

Note  10. — From  filtrate  (/),  the  filtrate  from  the  lead  sul- 
phate, precipitate  the  zinc  with  excess  of  sodium  carbonate, 
and  determine  the  zinc  oxide,  as  in  the  analysis  of  zinc  ore. 

After  precipitating,  and  filtering  out  the  zinc  carbonate, 
treat  the  filtrate  with  sulphuretted  hydrogen,  to  insure 


BARIUM    AND   CALCIUM    CARBONATES,    ETC.  171 

the  complete  x>recipitation  of  the  zinc.  Should  any  zinc 
sulphide  be  precipitated,  dissolve  it  in  hydrochloric  acid 
and  potassium  chlorate,  precipitate  with  excess  of  sodium 
carbonate  as  above,  and,  after  determining  the  amount  of 
zinc  oxide,  add  it  to  the  first. 

Note  11. — To  the  filtrate  from  the  sulphides  of  lead  and 
zinc,  or  filtrate  (e),  which  may  contain  acetates  of  calcium 
and  barium,  add  a  little  hydrochloric  acid,  and  dilute  sul- 
phuric acid,  to  precipitate  any  barium  present,  filter  out 
the  barium  sulphate,  and  wash  it  with  sodium  hyposul- 
phite, to  dissolve  out  any  calcium  sulphate  which  may 
possibly  be  present.  Weigh  the  barium  sulphate,  and 
calculate  it  to  barium  carbonate. 

Note  12. — To  the  filtrate  from  barium  sulphate,  or  fil- 
trate {g\  add  excess  of  ammonia,  and  a  sufficient  quantity 
of  solution  of  ammonium  oxalate,  filter  wash,  dry,  con- 
vert the  calcium  oxalate  into  sulphate  as  directed  in  the 
analysis  of  calcite,  and  calculate  to  calcium  carbonate. 

Note  13. — In  case  there  should  be  any  lead  oxide  in  the 
paint  not  combined  with  carbonic  or  sulphuric  acid,  it  will 
be  in  the  acetic  acid  solution  (a),  in  which  case  a  careful 
determination  of  the  carbonic  acid  must  be  made,  and, 
after  subtracting  enough  to  satisfy  the  calcium  existing 
as  calcium  carbonate,  the  remainder  should  be  calculated 
to  basic  carbonate  of  lead.  Should  there  be  any  lead  left 
unsatisfied,  it  is  to  be  calculated  to  lead  oxide.  It  must 
be  remembered,  however,  that  lead  sulphate  is  slightly 
soluble  in  acetic  acid,  and  a  slight  excess  of  lead  in  solu- 
tion (a)  may  be  due  to  this  cause. 

Appendix  1. — If  the  qualitative  analysis  shows  the  ab- 
sence of  sulphates  of  barium,  lead,  and  calcium,  should  there 
be  any  residue  left,  after  dissolving  the  paint  in  acetic  acid, 
dry,  ignite,  and  weigh  it,  as  it  is  probably  silica  or  clay, 
or  both.  Then  fuse  it  with  acid  sodium  sulphate,  digest 
the  fused  mass  with  sulphuric  acid,  dissolve  in  water, 
filter  out  the  silica,  and  in  the  filtrate  determine  the  alu- 
mina, and  calculate  the  clay  and  free  silica  as  in  Note  6. 


172  PAINT. 

If  no  silica  or  clay,  or  sulphates  of  barium,  lead,  or  cal- 
cium be  present,  acetic  acid  will  dissolve  the  paint  to  a 
clear  solution,  for  the  analysis  of  which  proceed  as  directed 
in  Notes  9,10,  11,  and  12. 

If  no  silica,  or  clay,  or  salts  of  calcium  and  barium  be 
present,  but  only  carbonate  of  lead  and  oxide  of  zinc,  the 
paint  may  be  dissolved  in  dilute  nitric  acid,  and  the  solu- 
tion, after  adding  sulphuric  acid,  treated  for  lead,  as 
directed  in  analysis  of  galena  ;  the  lead  calculated  to  basic 
carbonate  (white  lead),  and  the  zinc  precipitated  from  the 
filtrate  by  sodium  carbonate,  determined  as  in  the  analysis 
of  zinc  ore,  and  calculated  to  oxide. 

If  the  paint  be  a  pure  lead  paint,  dissolve  in  nitric  acid, 
and  determine  the  lead  by  evaporating  with  sulphuric 
acid,  and  proceeding  as  directed  in  the  analysis  of  galena. 
The  lead  is  to  be  calculated  to  basic  carbonate. 

If  it  be  a  simple  zinc  paint,  dissolve  in  nitric  acid,  pre- 
cipitate the  zinc  directly  with  sodium  carbonate,  and  weigh 
it  as  oxide,  as  in  analysis  of  zinc  ore. 

In  all  cases  where  zinc  is  precipitated  by  sodium  car- 
bonate, treat  the  filtrate  with  sulphuretted  hydrogen,  and 
if  any  zinc  sulphide  be  recovered,  filter  it  out,  dissolve  in 
hydrochloric  acid,  precipitate  with  sodium  carbonate,  and 
add  the  precipitate  to  the  first  one. 

Appendix  2. — In  paint  composed  of  sulphate  and  oxide 
of  lead,  and  containing  no  carbonate,  after  dissolving  in 
acetic  acid,  filtering,  and  washing  well,  dry,  ignite  as 
directed  in  analysis  of  galena,  and  weigh  the  lead  sul- 
phate. 

In  the  acetic  acid  solution,  determine  both  the  lead  and 
sulphuric  acid,  as  a  small  amount  of  lead  sulphate  may  be 
dissolved  by  the  acetic  acid.  Calculate  the  sulphuric  acid 
to  lead  sulphate,  and  add  it  to  that  found  in  the  residue. 
Deduct  the  amount  of  lead  due  to  lead  sulphate,  from  the 
total  lead  found  in  the  acetic  acid  solution,  and  calculate 
the  remainder  to  lead  oxide  (PbO),  existing  as  such  in  the 
paint. 


CHAPTER     XXX. 

FRESH   WATER. 

The  kind  of  analysis  required  depends  upon  the  use  to 
be  made  of  the  water,  whether  for  drinking  and  general 
domestic  purposes,  for  steam  boilers,  for  manufacturing 
purposes,  or  as  a  mineral  water. 

The  determination  of  its  value  as  a  potable  water  can  be 
made  by  a  short  and  simple  analysis,  showing  the  amount 
of  silica,  alumina,  and  oxide  of  iron,  lime,  magnesia,  soda, 
potash,  chlorine,  sulphuric  acid,  organic  and  volatile 
matter  (expelled  by  ignition  from  the  residue  left  after 
evaporating  a  given  quantity  of  water),  and  ammonia, 
both  free  and  in  a  form  styled  albuminoid,  which  latter  is 
thought  to  indicate  constituents  very  detrimental  to  health. 
Besides,  it  is  important  to  know  its  hardness,  or  soap  de- 
stroying power. 

This  analysis  will  furnish  all  the  information  that  is 
requisite  to  estimate  the  fitness  of  water  for  use  in  steam 
Iboilers,  and  for  manufacturing  purposes. 

The  analysis  of  mineral  water  is  much  more  complicated 
and  laborious,  and  will  be  described  later. 

Organic  and  Volatile  Matter.- — Evaporate  250  c.  c.  of  the 
water  to  dryness,  in  a  weighed  platinum  dish,  first  on  a 
water-bath,  and  then  in  an  air-bath  at  130°  C,  and  re- 
weigh  the  dish  with  its  contents.  Then  heat  the  dish,  at 
low-red  heat,  until  all  organic  matter  is  consumed,  and 
the  contents  are  white  or  nearly  so.  Then  add  25  c.  c.  of 
water,  saturated  with  carbon  dioxide,  evaporate  to  dry- 
ness on  a  water-bath,  repeat  the  treatment  with  carbon 
dioxide,  evaporate  on  a  water-bath,  dry  in  an  air-bath  at 
130°  C,  as  before,  cool,  and  weigh.  The  difference  between 
this  weight  and  the  first  expresses  the  amount  of  organic 
and  volatile  matter  in  the  quantity  of  water  taken. 


174  WATER. 

In  this  country  it  is  customary  to  report  analysis  of 
water  as  made  on  1  U.  S.  gallon  of  231  cubic  inches,  con- 
taining a  certain  number  of  grains,  which  number  has  been 
fixed  upon  in  the  Columbia  College  School  of  Mines  as 
58,318.  The  weights  and  measures  used  are  French.  This 
involves  a  short  calculation  to  convert  milligrammes  into 
the  corresponding  number  of  grains.  One  milligramme  is 
one  millionth  of  1  litre.  Suppose  that  upon  evaporating 
1  litre  of  water  1  milligramme  of  solid  matter  was  left,  the 
quantity  will  be  one  millionth  of  1  litre.  If  a  gallon  of 
the  same  water  were  used,  the  solid  matter  would  amount 
to  one  millionth  of  1  gallon,  or,  as  the  gallon  is  assumed 
to  contain  58,318  grains,  one  millionth  of  58,318,  and  any 
number  of  milligrammes  will  correspond  to  that  number 
of  millionths  of  58,318  grains.  Therefore,  the  number  of 
milligrammes  multiplied  by  58,318  and  divided  by  1,000,- 
000  will  give  the  number  of  grains  in  1  U.  S.  gallon  of 
231  cubic  inches.  This  rule  applies  to  the  calculation  of 
all  the  constituents  found  by  analysis.  Then,  to  deter- 
mine the  number  of  grains  of  organic  and  volatile  matter 
in  1  gallon  of  the  water  under  examination,  calculate  the 
number  of  milligrammes  which  would  be  lost  by  treating 
the  residue  left  after  evaporating  1  litre  of  the  water  as 
directed  above,  multiply  this  by  58,318,  and  divide  by 
1,000,000.  The  difference  between  the  weight  of  dry 
residue  before  ignition  and  the  sum  of  the  constituents 
found  by  analysis,  allowing  for  the  loss  of  the  water  and 
part  of  the  carbonic  acid  of  acid  carbonates,  should  not 
amount  to  more  than  a  small  fraction  of  a  grain.  If  it 
does,  the  analysis  should  be  repeated.  This  remark 
applies  only  to  water  containing  a  small  amount  of  mineral 
matter.  In  the  analysis  of  mineral  waters,  if  it  is  desired 
to  determine  the  "  total  solids  "  as  a  check  on  the  correct- 
ness of  the  analysis,  another  method  is  pursued,  which 
will  be  explained  later. 

Silica,  Lime,  Magnesia,  Alumina,  and  Oxide  of  Iron. — 
To  determine  these,  evaporate  in  a  platinum  dish  nearly 


-CHLORINE.  175 

to  dryness  on  a  sand-bath  (finishing  the  evaporation  to 
dryness  on  a  water-bath),  from  2  to  8  litres  of  water,  ac- 
cording to  the  purity  of  the  water,  having  previously 
acidulated  it  with  hydrochloric  acid.  Then  dry  the  residue 
in  an  air-bath  at  110°  C,  until  the  odor  of  hydrochloric 
acid  cannot  be  detected,  and  proceed  exactly  as  directed 
in  the  analysis  of  limestone.  For  this  part  of  the  analysis 
of  Croton  water,  5  litres  will  be  sufficient.  The  evapora- 
tion may  be  made  in  porcelain  instead  of  platinum,  but 
there  is  danger  of  introducing  a  small  amount  of  silica  and 
alumina  into  the  analysis.  As  in  the  analysis  of  water  of 
this  character  it  is  unnecessary  to  separate  the  small 
amount  of  alumina  and  oxide  of  iron,  they  are  generally 
weighed  together,  and  reported  as  alumina  and  ferric 
oxide. 

Sulphuric  Acid. — Acidulate  from  1  to  4  litres  of  the 
water  with  hydrochloric  acid,  evaporate  to  about  100  c.  c, 
filter,  if  necessary,  and  determine  S03  as  in  analysis  of 
magnesium  sulphate.  For  this  determination  in  Croton 
water,  2  litres  will  be  sufficient. 

Chlorine. — Evaporate  from  1  to  4  litres  of  the  water  to 
about  100  c.  c.  (2  litres  of  Croton  water  will  be  sufficient), 
and  determine  the  chlorine  volumetrically,  by  means  of  a 
standardized  solution  of  silver  nitrate.  The  determination 
is  made  by  first  adding  to  the  water  3  drops  of  a  saturated 
solution  of  potassium  chromate,  and  then  dropping  into  it 
the  solution  of  silver  nitrate,  from  a  burette,  until  the  red 
color  of  silver  chromate  appears.  The  number  of  c.  c.  of 
silver  nitrate  solution  used,  multiplied  by  the  value  of 
1  c.  c,  will  give  the  amount  of  chlorine.  This  is  calculated 
to  grains  in  a  gallon  as  above.  The  solution  of  silver 
nitrate  is  prepared  by  dissolving  it  in  distilled  water,  in 
the  proportion  of  17  gms.  of  the  pure  salt  in  1  litre  of 
water.  To  standardize  the  silver  nitrate  solution,  dissolve 
1  gm.  of  pure  fused  sodium  chloride  in  1  litre  of  distilled 
water,  pour  exactly  100  c.  c.  of  the  solution  into  a  beaker, 
add  3  drops  of  saturated  solution  of  potassium  chromate, 


178  WATER. 

and  drop  in,  from  a  burette,  the  silver  solution  until  the 
red  color  of  silver  chromate  appears.  The  Known 
quantity  of  chlorine,  in  the  100  c.  c.  of  salt  solution, 
divided  by  the  number  of  c.  c.  of  silver  solution  used,  will 
give  the  value  of  1  c.  c.  of  the  latter.  In  the  analysis  of 
water  containing  very  little  chlorine,  it  is  well  to  use  a 
centime  silver  nitrate  solution.  To  prepare  this,  run  10  c.  c. 
of  the  strong  solution  into  a  flask  holding  exactly  100  c.  c, 
fill  with  water  to  the  holding  mark,  and  mix  well. 

Soda  and  Potash. — Evaporate  from  1  to  10  litres  to 
about  100  c.  c.  according  to  the  character  of  the  water  (5 
litres  of  Croton  water  will  be  enough),  acidulate  slightly 
with  hydrochloric  acid,  then  add  saturated  solution  of 
barium  hydrate  until  the  fluid  is  strongly  alkaline,  boil, 
filter,  and  wash  well  with  hot  water,  to  remove  chlorides. 
From  the  filtrate  precipitate  excess  of  barium,  by  adding 
ammonium  carbonate  as  long  as  it  produces  a  precipitate, 
and  boiling.  Filter  and  wash  the  precipitate  of  barium 
carbonate  with  hot  water  until  the  washings  give  no  re- 
action for  chlorine.  Evaporate  the  filtrate  to  dryness,  and 
burn  out  the  ammonium  chloride  at  low-red  heat.  Take 
up  with  water,  and  repeat  the  treatment  with  barium 
hydrate,  and  ammonium  carbonate,  to  insure  the  complete 
removal  of  magnesium,  which  may  have  been  kept  in  solu- 
tion by  the  alkaline  chlorides.  Finally,  evaporate  the  fil- 
trate to  dryness  in  a  weighed  dish  (preferably  of  platinum), 
expel  any  ammonium  chloride  present,  at  low  red  heat ; 
cool  and  weigh  the  chlorides  of  sodium  and  potassium. 
Dissolve  the  contents  of  the  dish  with  water,  and  determine 
the  potassium,  as  directed  in  the  analysis  of  potassium 
alum,  and  calculate  the  sodium.  Consult  analysis  of  feld- 
spar. 

Hardness. — By  this  is  meant  the  soap-destroying  power 
of  the  water.  A  degree  of  hardness  means  the  effect  pro- 
duced on  a  solution  of  soap  by  water  containing  1  grain  of 
calcium  carbonate  in  a  gallon.  For  the  determination, 
there  will  be  required  a  solution  of  soap,  and  one  of  cal- 


HARDNESS.  177 

cium  chloride,  with  which  to  standardize  the  solution  of 
soap. 

Soap  Solution. — To  prepare  this,  dissolve  10  gms.  of 
good  soda  soap  (containing  about  12  per  cent  of  water),  in  1 
litre  of  90  per  cent  alcohol ;  filter,  and  keep  the  solution 
in  a  glass-stoppered  bottle,  and  mark  it  Strong  soap  solu- 
tion. For  use,  add  to  100  c.  c.  of  the  strong  solution  100 
c.  c.  of  water,  and  33  c.  c„  of  alcohol,  adding  the  alcohol 
before  the  water,  and  shaking  gently \  to  avoid  lathering. 

Calcium  Chloride  Solution. — To  prepare  this,  dissolve 
1  gm.  of  calcium  carbonate  in  dilute  hydrochloric  acid, 
evaporate  to  dryness  on  a  water-bath,  to  expel  all  free  acid, 
and  dissolve  the  residue  in  1  litre  of  distilled  water.  One 
c.  c.  of  this  solution  will  correspond  to  one  mgm.  of  calcium 
carbonate.  Dilute  10  c.  c.  of  the  solution  to  100  c.  c,  with 
distilled  water,  introduce  the  mixture  into  a  narrow  glass- 
stoppered  bottle,  which  holds  about  150  c.  c,  and  drop  in 
the  soap  solution  from  a  burette,  little  by  little,  intro- 
ducing the  stopper  into  the  bottle,  and  shaking  after  each 
addition  of  soap.  Continue  the  operation  until  a  perma- 
nent lather  is  formed,  which  will  remain  unbroken  for  5 
minutes.  The  lather  should  not  be  thick  and  frothy,  but 
only  a  light  pellicle  covering  the  surface  of  the  solution. 
When  it  breaks,  the  fluid  below  will  appear  in  patches. 
As  the  number  of  milligrammes  of  calcium  carbonate  in 
the  fluid  is  known,  when  the  number  of  c.  c.  of  soap  solution 
required  to  form  a  permanent  lather  is  also  known,  a  very 
simple  calculation  will  give  the  number  of  milligrammes 
that  1  c.  c.  of  the  soap  solution  is  equivalent  to. 

To  determine  the  hardness  of  a  sample  of  water,  intro- 
duce into  a  similar  bottle  100  c.  c.  of  the  water,  and  treat 
it  with  soap  solution  in  the  same  way  as  directed  for  stand- 
ardizing the  latter.  The  number  of  c.  c.  of  soap  solution 
required,  multiplied  by  the  value  of  1  c.  c,  and  this  prod- 
uct multiplied  by  10,  will  give  the  number  of  milli- 
grammes of  calcium  carbonate  in  the  litre  that  the  hardness 
of   the  water  is  equivalent  to.     This  number  of    milli- 


178  WATER. 

grammes  multiplied  by  58,318,  and  divided  by  1,000,000, 
will  give  the  corresponding  nnmber  of  grains  of  calcium 
carbonate  in  1  gallon,  or  degrees  of  hardness.  The  hard- 
ness of  water  may  be  due  to  the  presence  of  carbonates  or 
sulphates,  or,  though  rarely,  to  the  presence  of  free  acid. 
If  it  is  desired  to  determine  the  ' '  permanent' '  hardness, 
introduce  into  a  flask  holding  about  250  c.  c,  100  c.  c.  of 
the  water,  and  boil  for  half  an  hour,  to  precipitate  the  car- 
bonates held  in  solution  by  carbonic  acid,  make  the  solu- 
tion up  to  100  c.  c,  with  distilled  water,  and  determine  the 
hardness  as  before.  This  is  what  is  called  "permanent" 
hardness.  The  difference  between  this  and  the  hardness 
of  the  water,  before  boiling,  is  called  \ '  temporary' '  hard- 
ness. To  avoid  much  loss  by  evaporation  while  boiling, 
it  is  well  to  insert  into  the  mouth  of  the  flask  a  cork, 
through  which  passes  a  piece  of  glass  tubing,  about  3  feet 
long,  which  has  a  small  bulb  blown  in  it.  By  this  means 
the  steam  will  condense  and  run  back  into  the  tube. 
The  quantity  of  water  tested  should  not  contain  more  than 
12  milligrammes  of  calcium  carbonate.  If  it  does,  take  a 
smaller  quantity,  dilute  with  distilled  water  to  100  c.  c, 
and  proceed  as  before. 

This  determination  is  valuable,  as  it  will  often  obviate 
the  necessity  of  an  analysis  to  decide  upon  the  fitness  of 
water  for  manufacturing  purposes,  and  particularly  for  use 
in  steam-boilers. 

Permanganate  Test  (vid.  W.  A.  Miller,  Jour.  Lon. 
CJiem.  Soc,  1865,  XVIII.,  p.  117).— This  test  is  made  to 
determine  the  amount  of  oxidizable  organic  matter  in 
water,  and  is  claimed  by  some  able  chemists  to  be  equal  in 
value  to  the  determination  of  albuminoid  ammonia.  Dis- 
solve 0.7875  gm.  of  crystallized  oxalic  acid  in  1  litre  of 
distilled  water ;  then  1  c.  c.  of  the  solution  will  be  equiva- 
lent to  one  tenth  of  a  milligramme  of  oxygen,  as  0.7875 
gm.  of  oxalic  acid  (H2C204.2H20)  requires  0.100  gm.  of 
oxygen  to  become  carbonic  acid  (C02).  Then  dissolve  0.500 
gm.  of  potassium  permanganate  in  1  litre  of  water,  and 


PEKMANGANATE — XESSLEKIZING.  179 

dilute  until  1  c.  c.  of  the  solution  oxidizes  1  c.  c.  of  the 
oxalic  acid  solution.  Then  1  c.  c.  of  the  potassium  per- 
manganate solution  carries  one  tenth  of  a  milligramme  of 
available  oxygen.  To  200  c.  c.  of  the  water  add  3  c.  c.  of 
dilute  sulphuric  acid,  and  permanganate  solution  until  the 
color  ceases  to  disappear  for  three  hours.  From  the  num- 
ber of  c.  c.  of  permanganate  used,  calculate  the  quantity 
of  oxygen  required  to  oxidize  organic  matter.  It  is 
assumed  that  the  oxygen  required,  multiplied  by  8,  is 
equivalent  to  organic  matter.  (See  Tidy's  analysis  of 
London  water,  Reports  to  Local  Government  Board  on 
Metropolitan  Water,  1878.) 

Free  and  Albuminoid  Ammonia. — The  determination  of 
these  requires  what  is  known  as  ISFessler'  s  solution  ;  also  a 
solution  of  ammonium  sulphate  or  chloride  for  compari- 
son, a  strong  solution  of  sodium  carbonate,  one  of  potas- 
sium permanganate,  and  also  distilled  water  free  from 
ammonia.  (See  Water  Analysis,  Wanklyn  &  Chapman, 
4th  Ed.,  London,  1876,  pp.  20  et  seq.) 

Nesslef  s  Solution. — To  prepare  this  solution,  dissolve 
50  gms.  of  potassium  iodide  in  a  small  quantity  of  hot 
water,  place  the  solution  on  a  boiling  water-bath,  add, 
with  frequent  agitation,  a  strong  aqueous  solution  of  mer- 
curic chloride  (40  gms.  of  the  salt  and  300  c.  c.  of  water), 
until  the  red  precipitate  just  redissolves,  filter,  &dd  to 
the  filtrate  a  strong  solution  of  200  gms.  of  potassium 
hydrate,  filter,  dilute  to  one  litre,  add  5  c.  c.  of  a  saturated 
solution  of  mercuric  chloride,  allow  the  precipitate  formed 
to  settle,  decant  the  clear  fluid,  and  keep  it  for  use  in  a 
tightly  corked  bottle. 

Ammonium  Solution  for  Comparison. — Dissolve  0.3883 
gm.  of  ammonium  sulphate,  or  0.315  gm.  of  ammonium 
chloride,  in  1  litre  of  water,  and  1  c.  c.  of  either  solution 
will  contain  one  tenth  of  a  milligramme  of  ammonia 
(NH3).  For  use  dilute  to  ten  volumes,  and  then  1  c.  c.  will 
contain  one  hundredth  of  a  milligramme  of  ammonia. 

Sodium  Carbonate  Solution. — Add  100  gms.  of  sodium 


180  WATER. 

carbonate  to  200  c.  c.  of  distilled  water  free  from  ammonia, 
and  keep  in  a  well-corked  bottle. 

Potassium  Permanganate  Solution. — Dissolve  200  gms. 
of  potassium  hydrate  and  8  gms.  of  crystals  of  potassium 
permanganate  in  1  litre  of  distilled  water  free  from  am- 
monia, boil  hard  for  half  an  hour  in  a  two  litre  flask, 
to  expel  ammonia,  and  keep  in  a  well-corked  bottle. 

Distilled  Water. — Boil  distilled  water,  after  adding  a 
little  sodium  carbonate,  in  a  large  flask,  until  about  one 
fourth  is  evaporated,  then  distill  the  remainder  from  a  re- 
tort holding  about  1500  c.  c,  until  the  distillate  gives  no 
reaction  for  ammonia  with  Nessler  solution,  testing  50  c.  c. 
of  the  water  at  a  time.  When  no  more  ammonia  can  be 
detected,  distill  off  into  a  large  bottle  about  750  c.  c,  and 
test  again,  to  be  sure  that  the  750  c.  c.  are  free  from  am- 
monia. Proceed  in  the  same  way  until  enough  is  pre- 
pared, and  keep  the  pure  water  in  tightly-corked  bottles. 

Before  using  the  solutions  of  sodium  carbonate  and  po- 
tassium permanganate,  they  should  be  tested  for  am- 
monia. Introduce  into  a  retort,  holding  1500  c.  c,  1  litre 
of  water,  add  15  c.  c.  of  the  solution  of  sodium  carbonate, 
and  50  c.  c.  of  the  potassium  permanganate  solution,  and 
distill  until  the  distillate  gives  no  reaction  for  ammonia. 
Then  distill  500  c.  c.  of  the  water,  which  will  be  free  from 
ammonia.  Introduce  this  water  into  a  clean  retort,  add 
15  c.  c.  of  the  solution  of  sodium  carbonate,  and  distill 
until  the  distillate  ceases  to  give  a  color  upon  the  addition 
of  Nessler  solution,  and  determine  the  ammonia  as  di- 
rected later  and  note  the  amount  upon  the  bottle.  Then 
add  50  c.  c.  of  the  potassium  permanganate  solution,  and 
proceed  in  the  same  way,  marking  the  amount  of  ammonia 
found  upon  the  bottle.  The  solutions  should  be  tested 
frequently. 

Free  Ammonia. — Connect  a  retort  (of  capacity  of  at  least 
1  litre)  with  a  good  condenser,  cleanse  by  distilling  some 
clean  water  in  them,  introduce  500  c.  c.  of  the  water  to  be 
tested  and  15  c.  c.  of  the  Na^CC^  solution  ;   distill,  collect- 


FREE  AND   ALBUMINOID.  181 

ing  the  distillate  in  test  cylinders.  Meanwhile  place  in 
other  cylinders  of  the  same  calibre,  amounte  of  the  standard 
NH3  solution  containing  respectively  0.01,  0.02,  etc.,  mgm. 
NH3,  and  dilute  each  up  to  50  c.  c.  When  50  c  c.  have 
distilled  over,  add  1.5  c.  c.  of  Nessler  solution  to  each  cylin- 
der. Always  use  the  same  Nessler  solution,  and  the  same 
amounts,  and  allow  it  to  act  as  nearly  as  possible  for  the 
same  length  of  time.  After  a  few  minutes  compare  the 
tint  of  the  distillate  with  those  of  the  comparison  cylinders, 
and  thus  estimate  the  amount  of  ammonia  present  therein. 
If  the  water  is  likely  to  contain  much  ammonia,  it  will 
be  safer  to  mix  the  distillate  by  stirring,  take  out  10  c.  c, 
dilute  to  50  c.  c,  and  test  as  described  above.  The  re- 
maining four  fifths  of  the  distillate  may  be  used  to  confirm 
the  results  thus  obtained.  Test  each  succeeding  50  c.  c. 
of  the  distillate  in  the  same  way,  and  proceed  until  50  c.  c. 
contain  less  than  0.01  mgm.  NH8.  The  whole  amount  of 
ammonia  thus  determined,  less  that  due  to  the  15  c.  c.  Na2 
C03  gives  free  ammonia. 

Albuminoid  Ammonia. — When  the  distillation  with 
Na2C08  fails  to  show  ammonia,  add  50  c.  c.  of  the  perman- 
ganate solution  and  distill,  testing  each  successive  50  c.  c. 
of  the  distillate  as  before,  until  it  contains  less  than  0.01 
mgm.  ]STH3.  Deduct  ammonia  due  to  permanganate,  and 
the  result  is  albuminoid  ammonia. 

A  modification,  which  avoids  corrections  for  ammonia  in 
the  reagents,  may  be  stated  briefly  thus  :  Distill  200  to  3o0 
c.  c.  of  clean  water  with  15  c.  c.  Na.jC03  until  the  distillate 
is  free  from  ammonia ;  add  500  c.  c.  of  the  water  and  distill, 
testing  the  distillates  for  free  ammonia  ;  add  50  c.  c.  per- 
manganate solution  and  again  distill  clean  ;  then  500  c.  c.  of 
the  water,  and  test  distillates  for  total  ammonia.  The  differ- 
ence between  free  and  total  gives  albuminoid  ammonia. 

Nitrates      (vid.    Gladstone    and    Tribe,     Jour.     Lon. 

CJiem.  Soc,  June,  1873). — Evaporate  2  or  3  litres  of  the 

water  to  dryness  on  a  water-bath  after  adding  a  small  piece 

■  of  caustic  lime,  heat  the  mass  with  5  or  6  c.  c.  of  distilled 


182  WATEK. 

water,  and  rinse  it  into  a  200  c.  c.  flask,  connected  with  a 
small  Liebig  condenser,  which  is  also  connected  by  means 
of  a  glass  tube,  with  another  small  flask.  The  latter  flask 
is  provided  with  a  doubly-perforated  cork,  through  one 
hole  of  which  passes  the  tube  from  the  condenser,  and 
through  the  other  a  bent  glass  tube  connected  with  a  small 
U  tube  containing  a  little  broken  glass,  and  a  few  c.  c.  of 
dilute  hydrochloric  acid.  A  little  thin  sheet  zinc  (10  or  15 
gms. )  is  then  plated  with  copper  by  immersing  it  in  a  concen- 
trated solution  of  copper  sulphate  for  15  minutes,  and  in- 
troduce (after  washing  it  with  cold  water)  into  the  flask 
with  the  residue.  The  liquid  in  the  flask  is  gradually 
heated  to  boiling,  and  distilled  for  about  an  hour.  The 
distillate  and  washings  of  the  receiver  are  then  evaporated 
with  platinum  tetrachloride,  and  from  the  spongy  plati- 
num the  nitric  acid  calculated.  (Compare  analysis  of  am- 
monio-ferric  sulphate.) 

Grouping  the  Constituents  Found  by  Analysis. — It  is 
almost  impossible  to  give  rules  for  grouping  the  constitu- 
ents so  as  to  meet  all  cases.  It  will  be  sufficient  to  give 
directions  for  grouping  the  results  of  analysis  of  such 
water  as  is  at  all  likely  to  be  used  for  drinking  or  manu- 
facturing. Combine  the  sodium  with  chlorine  as  sodium 
chloride,  and  the  potassium  with  sulphuric  acid  as  potas- 
sium sulphate.  Should  there  be  any  more  sodium  than 
the  chlorine  will  satisfy,  and  more  sulphuric  acid  than  is 
required  by  the  potassium,  combine  the  excess  of  sodium 
with  sulphuric  acid  as  sodium  sulphate,  and  should 
there  be  more  sodium  than  the  sulphuric  acid  will  satisfy, 
calculate  the  excess  to  sodium  carbonate.  Should  there 
be  more  than  enough  sulphuric  acid  to  combine  with 
sodium  and  potassium,  combine  the  excess  first  with  cal- 
cium, as  calcium  sulphate,  and  any  further  excess  with 
magnesium  as  magnesium  sulphate.  If  the  water  contains 
a  large  amount  of  chlorine  (more  than  enough  to  satisfy 
the  sodium),  and  not  enough  sulphuric  acid  to  satisfy  the 
potassium,  combine  the  excess  of  potassium  with  chlorine,  , 


CALCULATION   OF   KESI7LTS. 


183 


and  if  there  be  any  chlorine  still  left,  combine  it  first  with 
magnesium,  and  then,  if  there  be  more  than  enough  to 
saturate  the  magnesium,  combine  the  excess  with  calcium. 
Calculate  all  calcium  and  magnesium  not  combined  with 
chlorine  and  sulphuric  acid  to  carbonates. 

The  following  table  may  be  found  of  use  in  the  analysis 
of  mineral  and  potable  waters  for  the  calculation  of  the 
number  of  grains  in  the  U.  S.  gallon  of  231  cubic  inches, 
the  number  of  milligrammes  per  litre  having  been  found. 
The  number  of  grains  in  the  gallon  has  been  taken  as 
58,318,  which  is  believed  to  be  the  most  correct  figure, 
though  authorities  on  the  subject  differ  slightly  from  one 
another,  e.  g.,  the  U.  S.  Dispensatory  gives  58,328.886,  or 
nearly  11  grains  more.  Either  of  these  results  gives  about 
133.3  avoirdupois  ounces  in  the  gallon. 

Table  showing  the  number  of  grains  in  the  U.  S.  gallon  of  231  cubic  inches,  corresponding 
to  the  number  of  milligrammes  in  one  litre,  by  E.  Waller,  A.  M.,  E.M. 


Mgs. 

to  1  Litre  = 

Mas. 

to  1  Litre  = 

Mgs. 

to  1  Litre  = 

Mgs.  tc 

1  Litre  = 

Grs. 

toU.  S.  Gal. 

Grs. 

to  U.  S.  Gal. 

Grs. 

to  U.  S.  Gal. 

Grs.  to 

U.  S.  Gal. 

1. 

...0.058318 

26. 

...1.516268 

51. 

. . .2.974218 

76.. 

.  .4.432168 

2. 

..0.116636 

27. 

. .  .1.574586 

52. 

. .  .3.032536 

77.. 

.  .4.490486 

3. 

...0.174954 

28. 

. .  .1.632904 

53. 

. .  .3.090854 

78.. 

.  .4.548804 

4. 

. .  .0.233272 

1      29. 

. .  .1.691222 

54. 

...3.149172 

79.. 

.  .4.607122 

5. 

...0.291590 

i   30. 

...1.749540 

55. 

...3.207490 

80.. 

.  .4.665440 

6. 

. .  .0. 34990s* 

31. 

...1.807858 

56. 

. .  .3.265808 

81.. 

.  .4.723758 

7. 

. .  .0.408226 

32. 

...1.866176 

57. 

. .  .3.324126 

82.. 

.  .4.782076 

8. 

. .  .0,468544 

33. 

...1.924494 

58. 

. .  .3.382444 

83.. 

.  .4.840394 

9. 

. .  .0.524862 

34. 

...1.982812 

59. 

. .  .3.440762 

84.. 

.  .4.898712 

10. 

. .  .0.583180 

35. 

. .  .2.041130 

60. 

. .  .3.499080 

85.. 

.  .4.957030 

11. 

. . .0.641498 

36. 

. .  .2.099448 

61. 

. .  .3.557398 

86.. 

.  .5.015348 

12 

...0.699816 

37. 

. .  .2.157766 

62. 

. .  .3.615716 

87.. 

.  .5.073666 

13. 

...0.758134 

38. 

...2.216084 

63. 

.  .3.674034 

88.. 

.  .5.131984 

14. 

. .  .0.816452 

39. 

. .  .2.274502 

64. 

.  .3.732352 

89.. 

..5.190302 

15. 

. . .0.874770 

40. 

. .  .2.332720 

65. 

.  .3.790670 

90.. 

.  .5.248620 

16. 

...0.933088 

41. 

. .  .2.391038 

66. 

.  .3.848988 

91.. 

.5.306938 

17. 

. .  .0.991406 

42. 

.  .2.449356 

67. 

.  .3.907306 

92.. 

.5.365256 

18. 

...1.049724 

43. 

.  .2.507674 

68. 

.  .3.965624 

93.. 

.5.423574 

19. 

...1.108042 

44. 

.  .2.565992 

69. 

.  .4.023942 

94.. 

.5.481892 

20. 

...1.166360 

45. 

.  .2.624310 

70. 

.  .4.082260 

95.. 

.5.540210 

21. 

...1.224678 

46. 

.  .2.682618 

71 

.  .4.140578 

96.. 

.5.598528 

22. 

. .1.282996 

47. 

.  .2.740946 

72. 

.  .4.198896 

97.. 

.5.656846 

23. 

..1.341314 

48. 

..2.799264 

73. 

.  .4.257214 

98.. 

.5.715164 

24. 

...1.399632 

49. 

.  .2.857582  1 

74. 

.  .4.315532 

99.. 

.5.773482 

25. 

...1.457950 

50. 

.  .2.915900  I 

75. 

.  .4.373850 

100.. 

.5.831800 

CHAPTER    XXXI. 


MINERAL   WATER. 


The  term  ''mineral"  is  usually  applied  to  water  possess- 
ing medicinal  properties,  or  an  unusual  amount  of 
mineral  matter.  It  is  not  proposed  here  to  discuss  the 
subject  of  mineral  water,  but  simply  to  give  methods  of 
analysis  of  two  leading  varieties — alkaline  carbonated 
water  and  sulphur  water,  that  of  Saratoga  being  an  illus- 
tration of  the  former,  and  that  of  Chittenango,  New  York, 
an  illustration  of  the  latter.  For  more  information  on  the 
subject,  the  student  is  referred  to  Fres.,  Quant.  Anal., 
§206,  et  seq.,  and  the  writers  quoted  by  him,  and  also  to 
Hunt' s  Chem.  and  Geolog.  Essays,  and  his  papers  in  Am. 
Jour.  Sci.  and  Arts,  1865. 

Saratoga  Water. — The  method  given  here  has  been  fol- 
lowed for  a  long  time  in  the  Columbia  College  School  of 
Mines,  having  originated  in  the  private  laboratory  of  Dr. 
C.  F.  Chandler.  The  constituents  provided  foi  are 
potash,  soda,  lithia,  lime,  magnesia,  strontia,  baryta, 
oxide  of  iron,  oxide  of  maganese,  alumina,  chlorine, 
bromine,  iodine,  fluorine,  sulphuric  acid,  phosphoric  acid, 
boracic  acid,  carbonic  acid,  and  silica. 

Total  Solids. — Evaporate  in  a  weighed  platinum  dish 
from  200  to  500  c.  c.  of  the  water,  on  a  water-bath,  and 
dry  thoroughly  in  an  air-bath  at  130°  C.  The  weight  of 
solid  residue  gives  a  control  of  the  analysis.  Fresenius, 
in  his  Quant.  Anal.,  §  213,  says  that  "  a  more  exact  con- 
trol is  attainable  as  follows  :  By  treating  the  residue,  on 
evaporation,  with  sulphuric  acid,  and  comparing  the  re- 
sidue of  the  sulphates  (the  iron  is  present  as  sesquioxide) 
with  the  sum  of  the  fixed  alkalies,  alkaline  earths,  and 
manganese  expressed  as  sulphates,  plus  the  sesquioxide  oJf 
iron,  the  silicic  acid,  and  the  phosphoric  acid  (as  HPO3)/1 


IRON,    LIME,    ETC. — SODIUM   CARBONATE.  185 

Oxide  of  Iron,  Alumina,  Lime,  Magnesia,  and  Silica. 
—Acidulate  1  litre,  or  more,  in  very  weak  waters,  with 
hydrochloric  acid,  evaporate  to  dryness,  take  np  with  hy- 
drochloric acid  and  water,  filter  out  the  silica,  and  weigh 
it.  Then  determine  the  silica  by  loss,  after  treating  with 
sulphuric  acid  and  ammonium  iiuoride.  Should  there  be 
any  residue,  fuse  it  with  a  little  sodium  carbonate,  digest 
with  water,  filter  out  and  wash  the  residue  insoluble  in 
water,  dissolve  it  in  hydrochloric  acid,  ard  examine  the 
solution  with  the  spectroscope.  Should  baryta  or  strontia 
be  present  in  appreciable  quantity,  determine  them.  The 
residue  will  probably  be  only  ferric  oxide,  which  is  to  be 
brought  into  solution,  and  added  to  the  filtrate  from  the 
silica.  Treat  the  filtrate  with  ammonia,  filter  out  the  pre- 
cipitate of  ferric  oxide  and  alumina,  dissolve  it  in  hydro- 
chloric acid,  and  reprecipitate  with  ammonia,  and  deter- 
mine the  ferric  oxide  and  alumina  together.  In  the  fil- 
trates, determine  the  lime  and  magnesia,  as  in  the  analysis 
of  limestone. 

Sulphuric  Acid. — Acidulate  1  litre  of  the  water  with 
hydrochloric  acid,  evaporate  to  small  volume  in  a  porce- 
lain dish,  and  deternine  the  sulphuric  acid  as  in  analysis 
of  magnesium  sulphate. 

Sodium  Carbonate. — Evaporate  1  litre  of  the  water  to 
dryness,  digest  the  residue  with  boiling  water,  filter,  and 
wash  until  the  washings  give  no  alkaline  reaction  with 
litmus  paper.  Carbonates  of  sodium  and  lithium  go  into 
solution.  To  the  filtrate  add,  in  slight  excess,  a  mixture 
of  calcium  chloride  and  ammonia  (prepared  by  dis- 
solving 60  gms.  of  calcium  chloride  in  250  c.  c.  of  water, 
adding  to  the  solution  100  c.  c.  of  ammonia,  filtering,  add- 
ing 100  c.  c.  more  ammonia,  and  diluting  to  500  c.  a). 
Reaction  will  take  place  between  the  calcium  chloride  and 
the  carbonates  of  sodium  and  lithium  in  the  water,  by 
which  calcium  carbonate  will  be  precipitated,  and  the 
chlorine  unite  with  the  sodium  and  lithium.  Filter  out 
the  calcium  carbonate,  and  wash  it  repeatedly  with  water 


186  MINERAL    WATER. 

until  the  chlorides  are  removed.  Then  dissolve  the  pre- 
cipitate through  the  filter  with  hydrochloric  acid,  precipi- 
tate the  calcium  as  oxalate,  and  determine  it  as  sulphate, 
as  in  analysis  of  calcite.  Estimate  the  corresponding 
amount  of  acid  sodium  carbonate. 

As  this  method  of  analysis,  intended  strictly  to  meet  the 
case  of  Saratoga  water,  is  applicable  in  most  points  to  the 
analysis  of  other  alkaline  carbonated  waters,  it  is  proper  to 
mention  that  in  some  cases  it  must  be  modified.  Sodium 
carbonate  may  exist  in  presence  of  excess  of  carbonic  acid 
and  of  magnesium  carbonate,  before  evaporating  the 
water,  but  by  evaporating,  calcium  carbonate,  magnesium 
sulphate  and  sodium  sulphate  will  be  formed.  (Hunt.) 
In  such  a  case  it  is  better  to  determine  the  alkalies  in  ex- 
cess over  what  is  required  to  combine  with  chlorine  and 
sulphuric  acid,  and  calculate  the  sodium  carbonate.  In 
such  cases,  determine  the  sodium,  as  directed  in  analysis 
of  fresh  water. 

Potas7i. — Evaporate  1  litre  of  the  water  nearly  to  dry- 
ness in  a  silver  or  platinum  dish,  filter,  and  wash  with 
boiling  water  until  the  washings  give  no  alkaline  reaction 
with  litmus.  If  the  water  is  strongly  saline,  evaporate 
one  tenth  of  the  solution,  on  a  water-bath,  to  the  consist- 
ency of  syrup,  after  acidulating  with  hydrochloric  acid, 
and  adding  an  amount  of  solution  of  platinum  tetra- 
chloride containing  platinum  tetrachloride  equal  in  weight 
to  four  times  that  of  the  chlorides  of  the  alkalies  present, 
and  determine  the  potash  as  directed  in  the  analysis  of 
potassium  alum. 

Should  there  be  any  sodium  salt  unconverted,  or  sodium 
platino- chloride  difficult  to  dissolve  in  the  alcohol,  filter, 
wash  on  the  filter  with  hot  water,  into  another  beaker, 
until  only  yellow  potassium  platino-chloride  is  left,  evap- 
orate the  filtrate  as  before,  after  adding  more  platinum 
tetrachloride,  filter,  and  combine  the  precipitates  of  pure 
potassium  platino-chloride,  and  determine  the  potassium. 

In  water    containing  soluble   salts  of  calcium,    partic- 


CHLORINE — CARBONIC   ACID.  137 

ularly  calcium  sulphate,  some  may  remain  with  the  platino- 
chloride  undissolved  by  the  alcohol,  and  be  found  with  the 
spongy  platinum  after  ignition.  In  such  a  case,  the  resid 
ual  platinum  may  be  purified  by  boiling  it  with  hydro- 
chloric acid  and  water,  filtering,  and  washing  thoroughly. 
The  better  plan,  however,  in  the  case  of  water  of  such 
a  character,  is  to  determine  the  potassium  as  in  the  analy- 
sis of  feldspar. 

Chlorine. — Determine  the  chlorine  in  25  c.  c.  of  the 
water,  after  diluting  it  with  about  100  c.  c.  of  distilled 
water,  by  a  standard  solution  of  silver  nitrate,  as  directed 
in  the  analysis  of  fresh  water.  In  water  containing  less 
chlorine  than  those  of  Saratoga,  a  larger  amount  must  be 
used  for  the  determination,  evaporating,  if  necessary.  The 
chlorine  may  be  determined  gravimetrically,  as  in  the 
analysis  of  barium  chloride.  It  must  be  borne  in  mind 
that  iodine  and  bromine  act  similarly  to  chlorine  on  the 
silver  solution,  and  that  a  proper  correction  must  be  made 
on  account  of  their  presence. 

Carbonic  Acid. — Introduce  into  each  of  several  bottles, 
of  a  capacity  of  about  300  c.  c. ,  and  provided  with  tightly 
fitting  glass-stoppers,  exactly  50  c.  c.  of  a  solution  of  cal- 
cium chloride  and  ammonia,  prepared  as  directed  in  the 
paragraph  on  sodium  carbonate,  and  introduce  into  each 
one  200  c.  c.  of  the  water,  at  the  spring,  before  the  free 
carbonic  acid  has  had  time  to  escape,  insert  the  stoppers 
slightly  greased  with  pure  tallow,  and  secure  them  with 
pieces  of  cloth  firmly  tied  to  the  necks  of  the  bottles. 
Afterward,  in  the  laboratory,  remove  the  stopper  from  a 
bottle,  cleanse  it,  as  well  as  the  neck  of  the  bottle,  from 
all  grease,  drop  it  again  loosely  into  the  neck,  place  the 
bottle  in  water,  and  boil  until  violent  effervescence  ceases. 
Then  filter  out  the  calcium  carbonate,  rinse  the  bottle 
thoroughly  with  water,  pouring  the  washings  on  the  same 
filter,  and  keep  the  bottle  for  further  treatment.  Wash 
the  calcium  carbonate  on  the  filter  as  long  as  the  wash- 
water  gives  any  reaction  with  ammonium  oxalate.     This 


188  MINEEAL  WATEE. 

washing  should  be  done  rapidly,  to  avoid  the  formation  of 
calcium  carbonate  by  the  carbonic  acid  in  the  atmosphere. 
Dissolve  the  calcium  carbonate  adhering  to  the  bottle  with 
a  little  hydrochloric  acid,  and  wash  into  a  beaker.  Then 
perforate  the  filter  with  a  rod,  wash  the  precipitate  through 
it  into  the  same  beaker,  cleansing  the  filter  with  hydro- 
chloric acid,  boil,  to  expel  free  carbonic  acid,  determine 
the  calcium  as  in  analysis  of  calcite,  and  calculate  the  car- 
bonic acid.  Confirm  the  results  by  treating  another 
bottle  in  the  same  way. 

Treatment  for  Substances  in  Minute  Quantities. — If  the 
water  is  not  alkaline  to  litmus  without  boiling,  it  is  better 
to  add  sodium  carbonate  until  the  water  has  a  slight 
alkaline  reaction,  as  otherwise  iodine  and  bromine  may  be 
lost  by  evaporation.  Evaporate  from  10  to  20  gallons  of 
the  water  to  dryness  in  an  even  number  of  porcelain 
dishes,  introducing  the  same  quantity  of  water  into  each, 
by  which  means  the  weighing  and  dividing  the  salts 
soluble  in  water  may  be  avoided,  as  will  be  seen  later. 
Complete  dryness  is  not  necessary.  Treat  the  residues 
with  hot  water,  boil,  decant  through  two  filters,  repeat 
the  treatment  several  times,  and  finally  throw  the  residues 
on  the  filters,  and  wash  until  no  trace  of  lithium  can  be 
detected.  If  it  is  found  to  be  difficult  to  wash  out  the 
lithium  from  the  residues,  it  is  well  to  wash  moderately, 
until  no  bromine  can  be  detected  in  the  washings,  and 
determine  the  lithium  in  the  residues. 

There  will  be — 1st.  Two  Insoluble  Residues.  2d.  Two 
Solutions. 

Treatment  of  the  Insoluble  Residues. 

First  Case. — If  lithium  be  not  present  in  the  water,  or 
be  completely  removed  by  hot  water,  dissolve  the  residues 
in  hydrochloric  acid,  combine  the  solutions,  evaporate  to 
dryness,  add  a  little  hydrochloric  acid  to  the  dry  mass, 
heat,  dilute  with  water,  and  filter  out  the  residual  silica, 
which  may  contain  sulphates  of  barium  and  strontium. 
Expel  the  silica  with  ammonium  fluoride  and  sulphuric 


IKON,    ETC. — BARIUM  AND   STRONTIUM.  189 

acid,  fuse  the  residue  with  sodium  carbonate,  digest  with 
water,  throw  the  mass  on  a  filter,  wash  out  alkaline  sul- 
phates, dissolve  the  carbonates  left  on  the  filter  with  hy- 
drochloric acid,  and  determine  the  barium  and  strontium  in 
the  manner  directed  later.  Divide  the  filtrate  from  the 
silica  into  3  equal  parts. 

Firsts  for  phosphoric  acid. 

Second,  for  iron  and  manganese. 

Third,  for  barium  and  strontium. 

Treatment  of  the  Part  for  Phosphoric  Acid. — Expel 
the  hydrochloric  acid,  and  convert  chlorides  into  nitrates 
by  evaporation  with  excess  of  nitric  acid,  diluting,  adding 
ammonium  molybdate,  and  proceeding  as  directed  in 
analysis  of  iron  ore. 

Treatment  of  the  Part  for  Iron  and  Manganese. — 
Precipitate  the  iron  as  basic  acetate,  filter,  dissolve  the 
precipitate  with  hydrochloric  acid,  and  precipitate  again, 
filter,  wash  with  hot  water,  combine  the  filtrates,  evaporate 
to  small  volume,  and  determine  the  small  amount  of  man- 
ganese, frequently  found  in  water  as  manganous  oxide,  as 
directed  in  analysis  of  manganese  ore.  Bring  the  basic 
acetate  in  sulphuric  acid  solution,  and  determine  the  iron 
by  titration  with  solution  of  potassium  permanganate,  as 
in  analysis  of  ammonio-ferric  sulphate. 

Treatment  of  the  Part  for  Barium  and  Strontium. — 
Dilute  the  solution  with  water,  add  dilute  sulphuric  acid, 
and  boil.  Enough  acid  should  be  added  to  precipitate  a 
little  calcium,  or  some  strontium  may  remain  in  solution. 
At  the  same  time  care  must  be  taken  not  to  precipitate  too 
much  calcium,  or  it  will  be  difficult  to  wash,  and  strontium 
may  be  lost  in  the  alcohol,  which  is  rarely,  if  ever,  abso- 
lute. The  precipitate  consisting  of  sulphates  of  barium 
strontium  and  calcium  should  be  treated  with  a  strong  so- 
lution of  ammonium  carbonate,  which  will  convert  the 
oxides  of  calcium  and  strontium  into  carbonates,  while 
fhe  barium  sulphate  will  be  unaffected.  The  carbonates 
are  then  dissolved  away  from  the  barium  sulphate  on  the 


190  MINERAL   WATER. 

filter,  with  cold  dilute  hydrochloric  acid,  the  barium  sul- 
phate washed  with  water,  dried,  ignited,  and  weighed, 
and  the  barium  calculated.  (H.  Rose,  Pogg.  Annal., 
XCV.,  286,  quoted  by  Fres.,  Quant.  Anal,  §  154,  3,  p. 
347.)  The  hydrochloric  acid  solution  is  evaporated  to  dry- 
ness with  excess  of  nitric  acid,  to  convert  the  chlorides 
into  nitrates,  and  the  nitrate  of  calcium  dissolved  out  with 
a  mixture  of  equal  parts  of  alcohol  and  ether.  (H.  Rose, 
p.  95.) 

The  residual  strontium  nitrate  is  dissolved  in  water,  and 
the  strontium  determined  as  sulphate.  (See  Fres.,  Quant. 
Anal.,  §  72,  p.  107.)  All  the  precipitates  should  be  tested 
by  the  spectroscope. 

Second  Case. — If  lithium  be  present,  and  be  not  com- 
pletely removed  by  hot  water,  which  will  be  almost  always 
the  case  if  there  be  much  in  the  water,  divide  the  hydro- 
chloric acid  solution  of  the  residues  insoluble  in  hot  water, 
into  4  equal  parts  (instead  of  3),  in  one  of  which  the 
lithium  is  to  be  determined,  while  the  other  3  are  to  be 
treated  as  directed  in  the  fir st  case. 

For  the  determination  of  the  lithium,  evaporate  the  solu- 
tion to  dryness  on  a  water-bath,  transfer  the  residue  to  a 
flask,  and  proceed  as  directed  later  for  the  determination 
of  lithium  in  the  water  solution.  Also  consult  Fres., 
Quant.  Anal.,  §209,  7,  4th  London  Ed.,  1865. 

Treatment  of  Water  Solutions. — There  will  be  two,  if 
the  plan  suggested  before,  of  evaporating  the  water  in 
separate  portions  has  been  followed.  Evaporate  each  to 
dryness,  and  appropriate  one  to  the  determination  of 
lithium,  and  the  other  to  the  determination  of  iodine  and 
bromine.  It  is  to  be  remembered  that  in  waters  contain- 
ing a  large  amount  of  chlorine,  and  also  barium  and 
strontium,  the  latter,  or  at  least  a  portion,  may  be  found 
in  the  water  solution,  instead  of  the  insoluble  residue,  and 
that  in  such  a  case,  a  portion  of  the  water  solution  must 
be  taken  for  their  determination. 
Lithium  and  Boracic  Acid. — When  the   solution  in 


LITHIUM — IODINE,    BROMINE,    ETC.  191 

which  the  lithium  is  to  be  determined  has  been  evaporated 
to  very  small  volume,  pour  about  1  c.  c.  of  it  into  a  watch- 
glass,  acidulate  it  with  hydrochloric  acid,  and  test  it  with 
turmeric  paper  for  boracic  acid,  traces  of  which  are  gen- 
erally found  in  water  of  Saratoga.  Wash  back  the  fluid 
used  for  the  test,  and  continue  the  evaporation  to  dryness. 
Then  moisten  the  dry  residue  with  hydrochloric  acid, 
evaporate  again  to  dryness  on  a  water-bath ;  dry  heat 
must  not  be  used,  as  the  lithium  chloride  is  very  easily 
decomposed  by  heat,  being  converted  into  oxide  which  is 
insoluble  in  absolute  alcohol.  After  evaporating  the  ex- 
cess of  hydrochloric  acid,  transfer  the  dry  residue  to  a 
capacious  flask,  agitate  well  with  absolute  alcohol,  decant 
through  a  filter,  repeat  until  the  residue  gives  no  reaction 
for  lithium  in  the  spectroscope,  evaporate  the  alcohol  on  a 
water-bath,  and  dissolve  the  residue  in  water. 

As  magnesium  carbonate  is  not  entirely  insoluble  in 
water  in  presence  of  chlorides,  some  magnesium  will  be 
found  in  the  solution  resulting  from  the  treatment  of  the 
residue  of  the  original  evaporation,  and  must  be  removed 
before  determining  the  lithium  as  phosphate.  To  effect 
the  removal  of  magnesium,  make  the  solution  alkaline 
with  the  barium  hydrate,  filter,  and  from  the  filtrate  pre- 
cipitate the  excess  of  barium  with  ammonium  carbonate, 
add  to  the  filtrate  about  6  gms.  of  pure  hydro-disodium 
phosphate,  enough  pure  sodium  hydrate  to  keep  the  reac- 
tion alkaline,  and  evaporate  the  mixture  to  dryness ;  pour 
water  over  the  residue  in  sufficient  quantity  to  dissolve 
the  soluble  salts  with  the  aid  of  a  gentle  heat,  add  an  equal 
volume  of  ammonia,  digest  at  a  gentle  heat,  filter  after  12 
hours,  and  wash  the  precipitate  with  a  mixture  of  equal 
volumes  of  water  and  ammonia.  Evaporate  the  filtrate 
and  first  washings  to  dryness,  and  treat  the  residue  in  the 
same  way  as  before.  If  some  more  lithium  phosphate  is 
thereby  obtained,  add  this  to  the  principal  quantity.  (See 
Pres.,  Quant.  Anal.,  §  100,  p.  164.) 

Iodine,  Bromine,  and  Nitric  Acid. — Evaporate  thesolu- 


192  MINERAL    WATER. 

tion,  in  which  these  are  to  be  determined,  to  dryness, 
transfer  the  dry  residue  to  a  capacious  flask,  and  boil  on 
a  water-bath  repeatedly,  with  85  per  cent  alcohol,  de- 
canting on  a  filter  each  time,  until  the  residue  gives  no  re- 
action for  bromine,  when  treated  with  fuming  nitric  acid 
and  carbon  disulphide.  Evaporate  the  alcohol  on  a  water- 
bath,  and  when  the  alcohol  is  expelled,  test  a  little  of  the 
substance  for  nitric  acid.  To  determine  nitric  acid, 
evaporate  a  separate  portion  of  the  water,  and  proceed  as 
directed  in  the  analysis  of  fresh  water.  After  expelling 
the  alcohol,  wash  the  residue  into  a  platinum  dish,  add 
about  5  times  its  weight  of  sodium  carbonate,  dry,  and 
fuse.  This  is  done  to  decompose  any  organic  matter  which 
may  be  present,  either  from  having  been  held  in  the  water 
originally  or  extracted  from  the  vessels  in  which  the  water 
was  collected.  Organic  matter  must  be  removed,  or  it 
will,  upon  the  addition  of  palladium  chloride,  cause  a  pre- 
cipitate of  palladium  oxide  with  the  iodide,  and  thereby 
vitiate  the  determination.  Dissolve  the  fused  mass  in 
water,  acidulate  slightly  with  hydrochloric  acid,  add 
slight  excess  of  palladium  chloride,  allow  the  whole  to 
stand  for  24  hours  in  a  warm  place,  filter  out  the  pal- 
ladium iodide,  wash  with  warm  water,  dry,  ignite,  and 
from  the  metallic  palladium  calculate  the  iodine. 

To  the  filtrate  from  the  palladium  iodide  add  sodium 
carbonate  in  excess,  evaporate  to  dryness,  digest  the  dry 
residue  with  boiling  absolute  alcohol,  decanting  on  a 
filter,  and  repeating  the  treatment  until  the  residue  gives 
no  reaction  for  bromine,  when  tested  with  fuming  nitric 
acid  and  carbon  disulphide.  When  the  bromine  is  all  ex- 
tracted from  the  residue,  evaporate  the  alcoholic  solution 
to  dryness,  after  adding  a  little  sodium  hydrate,  dissolve 
the  dry  residue  in  water,  add  excess  of  silver  nitrate, 
filter  out  the  precipitate  of  bromide  and  chloride  of  silver, 
wash  with  hot  water,  dry  the  precipitate,  fuse  it  in  a 
weighed  porcelain  crucible,  and  weigh.  Then  pour  water 
on  the  fused  mass  in  the  crucible,  add  a  little  hydrochloric 


BROMINE — CALCULATION.  193 

acid  and  a  fragment  of  zinc.  In  24  hours,  the  silver  will  be 
completely  reduced.  The  silver  is  then  rubbed  to  powder, 
boiled  with  water  containing  a  little  hydrochloric  acid, 
washed  with  pure  water,  gently  ignited,  and  weighed. 
The  difference  between  the  atomic  weights  of  chlorine  and 
bromine  is  to  the  atomic  weight  of  bromine  as  the  differ- 
ence between  the  amount  of  chloride  and  bromide  of  silver 
employed,  and  the  amount  of  chloride  which  the  reduced 
silver  ought  to  yield  is  to  the  amount  of  bromine  present. 
(See  Wohler's  Mineral  Analysis,  p.  213;  and  Fres., 
Quant.  Anal.,  §  169,  p.  412.) 

As  silver  chloride  is  not  absolutely  insoluble  in  hydro- 
chloric acid,  it  is  well  to  test  the  fluid,  after  treating  the 
reduced  silver  with  hydrochloric  acid  to  remove  any  traces 
of  zinc  remaining  with  the  silver,  and  if  any  silver  chloride 
be  recovered,  add  the  weight  of  it  to  that  calculated  from 
the  reduced  silver,  before  making  the  calculation  as  direct- 
ed above.  On  the  other  hand,  as  a  slight  amount  of  chlo- 
ride may  escape  reduction,  it  is  well  to  treat  the  reduced 
silver  with  a  little  ammonia,  filter,  wash,  ignite,  and  weigh 
the  silver  again.  The  loss  will  be  silver  chloride.  Estimate 
the  chlorine  in  it,  and  substract  it  from  the  first  weight. 
After  making  these  corrections,  calculate  the  bromine. 

Calculation  of  the  Analysis. — The  sulphuric  acid  is 
combined  with  potassium  to  form  sulphate. 

The  potassium  unsatisfied  by  sulphuric  acid  is  combined 
with  chlorine  to  form  potassium  chloride. 

The  chlorine  not  required  by  potassium  is  combined  with 
sodium  to  form  sodium  chloride. 

The  bromine,  iodine,  phosphoric  acid,  boracic  acid,  and 
nitric  acid  are  combined  with  sodium,  to  form  bromide, 
iodide,  phosphate,  biborate,  and  nitrate. 

The  sodium  bicarbonate  is  determined  directly. 

The  sodium  is  not  determined,  but  is  assumed  as  the  sum 
of  all  required  to  combine  with  chlorine,  bromine,  iodine, 
phosphoric  acid,  boracic  acid,  nitric  acid,  and  carbonic  acid. 

The  lithium,  magnesium,  calcium,  less  that  for  fluorine, 


194 


MINERAL    WATER. 


strontium,  barium,  iron,  and  manganese,  are  combined 
with  carbonic  acid  tc  form  bicarbonate. 

The  fluorine  is  calculated  to  calcium  fluoride. 

The  alumina,  silica,  and  organic  matter  are  reported  as 
such. 

Sulphur  Waters. — The  constituents  of  these  waters  are 
very  similar  to  those  found  in  most  spring  waters,  with 
the  exception  of  the  sulphur  compounds,  as  will  be  seen 
by  the  subjoined  report  of  analyses  of  the  waters  of  Chit- 
tenango,  Madison  Co.,  "N.  Y.,  taken  from  a  lecture  of  Dr. 
C.  F.  Chandler,  published  in  Am.  Chem.,  December,  1871. 

ANALYSIS  OF  SULPHUR  WATERS. 


In  One  U.  S.  Gallon  of  231  Cubic 

Chittenangc 

>,  Madison  County,  N.  Y. 

Florida 

Spring, 

Montgom'ry 

Co.,  N.  Y. 

Inches. 

White  Sul- 
phur Sp'g. 

Cave  Spring. 

Magnesia 
Spring. 

Hydrosulphate    of     sodium, 
NaHS 

Grains. 
0.117 

oiii 

81.420 

Trace. 

1.953 

22. 017 
0.078 
0.156 
1.037 

Trace. 
0.082 
0.288 

Trace. 

Grains. 
0.3S6 
1.123 

106'.  126 
Trace. 

7.589 
0.257 

23.973 
0.156 
0.233 
1.569 

Trace. 
0.222 
0.519 

Grains. 
0.757 
0.929 

115.085 
Trace. 

12.718 
0.020 

20*.  779 
0.325 
0.333 
1.833 

Trace. 

Trace. 
0.577 

Grains. 
2.008 

Hydrosulphate  of  calcium  Ca 
(HS)o 

Sulphate  of  potassa 

Sulphate  of  soda 

1.390 

Sulphate  of  lime 

Sulphate  of  strontia 

Sulphate  of  magnesia 

.... 

Hyposulphite  of  soda 

0.711 

Bicarbonate  of  soda,  NaHC03. 

22.143 
8.317 

Bicarbonate  of  magnesia 

Bicarbonate  of  iron 

Chloride  of  potassium 

6.972 

5*.  880 

Trace. 

Silica                       

0.79a 

Sulphur  (in  suspension) 

Sulphide  of  iron  (in  suspension) 

0'.176 

Total  solid  contents  per  gallon 

Total  sulphur  in  the  metallic 

sulphides  and  sulphuretted 

107.359 
0.339 

142.113 
1.397 

153.356 
2.400 

43.390 
1.9165 

CUBIC  INCFI 

:s  OF  GAS 

PER  GALLO 

N. 

Sulphuretted  hydrogen  gas 

0.884 
20.480 

2.754 

15.934 

5.623 
19.456 

3.765 
32.169     . 

— • 

THE  FOLLOWING  STATEMENT  OF  ANALYSES  OF  SARATOGA  WATER  IS  TAKEN  FEOM  A  LECTURE  ON  WATER,  DELIVERED  BY  DR.  C.  F.  CHAND. 
LER,  AND  PUBLISHED  IN  THE  AMER.  CHEMIST,  DECEMBER,  1871. 

ANALYSES  OF  SOME  OP  THE   SPRINGS  AND  ARTESIAN  WELLS  OP  SARATOGA    COUNTY,  N.  Y. 


In  Saratoga. 

In  Ballston. 

compounds  as  they  exist  in 
Solution  in  the  Waters. 

Star 
Spring. 

High 

Rock 
Spring. 

Seltzer 
SpriDg. 

Pavilion 
Spring. 

United 

States 
Spring. 

Hathorn 
Spring. 

Crystal 
Spring. 

Congress 
Spring. 

Geyser 

swei'rg 

Vichy. 

Emnire     Glacier 

Ballston 

Artesian 
Lithia  Well 

Franklin  1     Conde 
Artesian     Deniimiuu 
Well.            Well. 

Chloride  of  sodium 

398361 

9 -095 

0  126 

1  586 
12-002 
01  ill  2 

124-459 

Trace. 
0-096 
1-213 
5-400 

Trace. 

Trace. 

Trace. 

Trace. 

390-127 
8-974 
0-731 
0086 
Trace . 
1-967 

54-924 
131-739 

Trace. 
0494 
1-478 
1-608 

Trace. 

Trace. 
1-223 
2-260 

134-291 
1-335 

0-031 

459-903 
7  660 
0-987 
0-073 

141-872 
8-624 
0-844 
0  047 

509-968 
9  597 
1-534 
0-198 

328-468 
8-327 
0-414 
0-066 
Trace. 
4-326 
10-064 
75  101 
101-881 

Vfle 

2-038 
2158 

Trace'. 
0-305 
3213 

400-444 
8-049 
8-559 
0-138 
Trace. 
4-761 
10-775 
121-757 
143-399 

0-92S 
0-340 
0-889 

750-030 

33-276 
3-643 
0-124 

Trace. 
7-750 

11-928 
180-602 
238-156 
0-867 
3-881 
1-581 
0-520 
0  050 

Trace. 
0-077 
0-761 

Trace. 

Chloride  of  potassium 

Bromide  of  sodium 

Iodide  of  sodium  

24  034        14-113 
2-212          0990 
0-248       Trace. 

8-733 
1307 
0039 

Trace. 
2-605 

17-010 
109-0S5 

90-703 

1-818 
0  026 

Trace. 
0  324 
2  653 

Trace. 

4292        40-440 
0-266          3-579 
0606           0-234 

33-9311 

0-235 
Trace. 
6-777 
94-604 
177-808 
2,12  332 
0-002 
1-231 
1-009 
0-762 

9232 
2-368 
0-225 

Trace. 

10-514 

34-400 
158-348 
178-484 
0-189 
4-739 
2-296 

Trace. 

Bicarbonate  of  lithia 

Bicarbonate  of  soda 

Bicarbonate  of  magnesia 

Bicarbonate  of  lime 

;:    arbonate  of  sti-ontia 

Bicarbonate  of  baiyta 

Bicarbonate  of  iron 

:  '.nl|  .I-iuli-  <»l    1"  .l.'s;;;i 

0-8991         9-486 
29428           3-764 
40-339        76-207 
89-869       120-169 

Trace.        Trace. 

Trace.  1         0-875 
1-703         2-570 
0-557          2-032 

Trace.!        0-007 

Trace.        Ti-aci-. 

2-561          3-155 
Trace.  1      Trace. 

4847        11-447 

^4- i         .-■"-'** 

93-Vui      riii-o-o; 

0-018:      Trace. 

0-909!         1-737 

0-714          1-128 
Trace. !      Trace. 

0-016,        0-006 

7-004 
71-232 
149-343 
170-393 
0-425 
2-014 
0-979 
0  318 

1-760 

82-873 
41-503 
95-522 
Trace. 

0  593, 

S£=  - 

Trace. 

Trace. 
0-473 
0-758 

Trace. 

2-080 
9022 
42-953 
109-056 
Trace. 
0-070 
0-793 

0023 
Trace. 
0-418 
1-458 
Trace. 

6-247 
17-624 
193-972 
227-071) 
0-082 
2-083 
0.647 
0-252 

o-oio 

Trace. 
0-458 
0099 

Trace. 

Trace.'      Trace. 
Trace.  I      Trace. 
0-840]        0-665 
Trace.1      Trace. 

Alumina        

Silica  

0094 
3-184 
Trace. 

0-131 
1-260 
Trace. 

0263              0-395 
0-735;             1.02e 

Total  per  U.  S.  gal.,  231  cu.  in. 

617-367 

630-500 

302-017     687-275 

331-837 

888-403J     537-155 

700-895      991-546 

367-326 

701-174 

680-430 

1,195-582 

1,233-240 

1,184-368     1,047-700 

407650 

1-0091 

4  09-458 
1-0092 
52°  P. 

3-;  4  1180      332-458 

24  .V  734 
1-0035 

383-071 

384  2101 

344-009 

405-458 

1        426-114 
1-0159 
j      52°  F. 

460-066 

10135 
52°  F. 

, 

1-0115 

1-OO60 
50°  P. 

1-096 
52°  F. 

Temperature 

50°  F. 

46°  F. 

50°  P. 

48°  P. 



BASES  AND  ACIDS,    AS  ACTUALLY  FOUND  IN    THE  ANALYSES,    UNCOMBINED. 

7-496 

160-239 
0-163 

43024 

Trace. 
0-056 

11.-992 
0491 

Trace. 

246-357 

0  443 

0-106, 

Trace.! 
2-483 

Trace. 

Trace. 

56-606 

56-606 
1-283 

Trace. 

33160 
0-496 
0-187 
1-206, 

5-419 

'ii-i-o-.' 

45-540 

Trace. 
0-292 

15-048 
0-598 
1  -223 
241017 
0-568 
0072 

Trace. 
0-739 

Trace. 

62-555 

62555 

2-200 
Trace. 
25 -.591 
0  148 
0-232 

61-003 
•     0-093 
31-066 
Trace. 
Trace. 

J  1-051 

0-374 

82128 

0-026 
Trace. 

0-256 
Trace. 
Trace. 

44-984 

44-984 
2-561 

Trace. 

18-405 
0-051 
0-105 
2-803 

4-931 

183(181 

0-976 
41-540 
Trace. 

0-517 

20 -8!  15 
1-040 
0-329 
282-723 
0-767 
0-060 

0934 
0-004 
Trace. 

60-461 

60-461 
3155 

Trace. 

24-736 
0-187 
1-116 
0  358 

o-ooi 

4-515 

57-259 
0-499 

32  189 
0-009 
0-537 

19-908 
0-289 
0094 

90-201 
0-656 
0-039 

Trace. 

Trace. 
0-008 

Trace. 

50380 

3184 
Trace. 
20-613 

5-024 

202-058 
1-179 

58-989 

Trace. 
1-026 

48-340 
0-456 
0131 
314(137 
1-188 
0-166 

Trace. 

Trace. 
0-003 

Trace. 

104-928 

104-928 

Trace. 
42-929 

5-326 

132-006 

0  445 

35-218 

Trace. 
0-429 

20-592 
0  824 
0-305 
203-292 
0  322 
0-055 

Trace. 
0-992 
0-004 

Trace. 

54-984 

54-984 
3-213 

Trace. 

22-4:>i; 
0199 
0-509 
0959 

4  611 

102-321 
0-490 

49-56! 

Trace. 
0-549 

33-358 

Trace. 

2  10-834 
0-045 
0-117 

Trace. 
0-409 
0-008 

Trace. 

80-249 

80-249 
0-840 

Trace. 

33-828 
0  082 
0-563 
1-024 
0-002 

13-039 

251-031 
0-720 

58901 
0  211 
1190 

40-915 
0  396 

Trace. 

352-825 
1-718 
0-208 

Trace. 
0-146 

Trace. 

Trace. 

112-880 

112  880 
0-665 

Trace. 

46-183 
0  029 
0824 

7-400 
0181 

0  350 
11-370 

0-021 

0-473 
84-807 

0-769 
Trace. 
Trace. 
Trace. 

Trace. 

60-840 

60-839 
0-758 

Trace. 

24-891 



0-207 
7-893 

5-487 
185- 151 

0-268 
33-428 
Trace. 

1-007 

30-1151 

o-ioo 

0-324 

282-175 

1-015 

0  033 

Trace. 
0-835 
0013 

Trace. 

64-974 

64-974 

2-653 
Trace. 

0-302 
1-620 
0-003 

3-492 

302-9  1: 
0  214 
37  906 

21-312 
281758 
0643 
78-493 
0-040 
1-230 
53-142 
0  263 
0-458 
445-392 
2-780 
0198 

17-653 

299-005 

0-798 

82326 
0-430 
2  292 

49-480 

0-077 

470-097 

2829 

0-104 

Trace. 
0-239 
0-025 

Trace. 

125-973 

125973 
0-761 

Trace. 

51-543 
0-048 
0911 
1-136 
0  006 

18-104 

286  221 

0-608 

69-942 
0001 
0-727 

48-731 
0-651 
0-203 
416-278 
3-623 
0-197 

0-350 
0000 
Trace. 

136133 

136133 
0-735 
Trace. 

'o-070 
0-797 
9-011 

o-ooi 

4833 

Lithium 

1-082 

0-041 
11-768 
0  321 
0-418 
308-357 
0-107 
0-513 

Magnesia 

Protoxide  of  iron 

Chlorine 

43  383 
0-929 
0-395 

390-090 

Iodine 

0189 

••"i-272 
0  011 

0-115 
0  005 

l'linsplH»ncacidtP20B) 

Oarboiiic  *>cid  (C02)  in  carbon- 
ates  

1  Carbonic  acid  (COa)for  bicar- 

45-972 

45-972 
1-458 

18-720 

0-215 

0-005 

127-298 

127-298 
0-699 

"' 52-077 
0023 
0-735 
1-678 

o-ooi 

110-019 

Silica 

Organic   matter 

Wat i-r  in  bicarlionates 

Oxygen  in  K2S04 

<  .xvrmi  in  Lit  ICO, 

1026 
Trace. 
45013 

0-570 
0  444 
0-002 

1-347 
0-408 

o-ooi 

1-237 
3-277 

Trace. 

Total  per  U.  S.  gal.,  231  cu.  in. 

(i  17-307 

630-500 

302-007 

687-275 

331-837 

888-403 

537-155 

700-895 

901-546 

307-320 

701  174 

680  430 

1,165-582 

1,233246 

1,184-368 

1,047-700 

Total  residue  by  evaporation. 

537-600 

542-350 

238-970 

602-080 

260840 

740-550 

459070 

588-818 

S32-4  83 

281-595 

609-613 





1,055-730 

992540 

892-670 

;ime  to  time 


SULPHUR  COMPOUNDS   IN   WATER.  195 

'  •'  The  analyses  were  made  in  the  Editor' s  laboratory, 
with  the  assistance  of  W.  H.  Chandler  and  F.  A.  Cairns." 

The  evaporation  of  large  quantities  of  the  water,  and 
the  determinations  of  the  ordinary  constituents  are  made 
in  the  way  directed  in  analysis  of  Saratoga  water. 

Sulphur  Compounds. — The  following  extract  from  the 
Cliem.  News,  American  Supplement,  April,  1870,  gives 
the  method  of  determining  the  sulphur  compounds  :  k '  The 
method  employed  for  determining  the  sulphur  compounds 
was  a  modification  of  the  one  employed  by  Simmler  in  the 
analysis  of  the  Stachelberg  water,  the  account  of  which 
was  published  in  Erdmanrt  s  Journal,  Yol.  LXX.  The 
alterations  introduced  lessen  to  a  great  extent  the  amount 
of  analytical  work  to  be  done  at  the  spring.  The  follow- 
ing brief  statement  may  prove  of  interest : 

"1.  In  a  glass-stoppered  bottle,  to  one  litre  of  water  was 
added  an  excess  of  neutral  solution  of  nitrate  of  silver. 

"  2.  To  another  litre  was  added  an  excess  of  a  solution  of 
chloride  of  cadmium. 

"  3.  Through  a  third  litre  pure  hydrogen  was  transmitted 
until  the  gas,  after  passing  through  the  water,  no  longer 
decolorized  a  dilute  solution  of  iodide  of  starch.  An  ex- 
cess of  a  solution  of  chloride  of  cadmium  was  then 
added. 

' '  These  three  bottles  vvere  well  agitated,  securely  sealed, 
and  transported  to  the  laboratory.  From  each,  the  precip- 
itate was  filtered,  washed,  dissolved,  and  oxidized  by 
fuming  nitric  acid  and  potassium  chlorate,  filtered,  and 
the  sulphuric  acid  determined  in  the  filtrate  with  barium 
chloride. 

"  No.  1.  This  precipitate  contained  the  sulphur,  existing 
in  the  form  of  sulphides  and  hyposulphites. 

"No.  2.  Contained  the  sulphur  existing  in  the  form  of 
sulphides,  including  the  free  sulphuretted  hydrogen. 

"No.  3.  Contained  the  sulphur  present  in  the  form  of 
sulphuretted  sulphides.  The  difference  between  No.  3 
and  No.  2  indicated  the  amount  of  sulphur  as  free  sul- 


196  MINERAL   WATER. 

phuretted  hydrogen  ;  and  by  deducting  No.  2  from  No.  1, 
the  amount  of  hyposulphites  was  ascertained. 

uIn  the  original  nitrate  from  No.  1,  the  sulphuric  acid 
was  determined,  after  removing  the  excess  of  silver  by 
hydrochloric  acid." 

The  changes  made  in  Simmler  s  method  were  suggested 
by  Wm.  H.  Chandler.  Bromine  may  be  used  instead  of 
nitric  acid  and  potassium  chlorate  in  oxidizing  the  pre- 
cipitates containing  sulphur. 


CHAPTER    XXXII. 

SUPERPHOSPHATE   OF   LIME. 

{For  Agricultural  Purposes.) 

It  is  so  called  from  the  fact  that  by  treatment  with  acid 
the  common  tri-calcinm  phosphate  (bone  phosphate)  is. 
converted,  according  to  the  quantity  of  acid  used,  into 
either  mono-calcium,  or  di-calcium,  phosphate.  If  a  suf- 
ficient quantity  of  sulphuric  acid,  for  instance,  be  used,  all 
the  calcium  will  be  withdrawn,  and  only  phosphoric  acid 
be  left.  The  treatment  for  the  production  of  soluble  phos- 
phate or  superphosphate  is  represented  by  the  following 
equation  : 

Ca3(P04)2+2H2S04=2CaS04+CaH4(P04)3. 

This  is  theoretical,  and  is  rarely  carried  out  in  the  manu- 
facture of  fertilizers.  There  is  usually  some  bone  phos- 
phate unconverted,  owing  to  the  use  of  an  insufficient 
quantity  of  acid.  Suppose  some  tri-calcium  phosphate  to 
remain  mixed  with  mono-calcium  phosphate,  and  reaction 
to  take  place  between  them,  as  represented  by  the  follow- 
ing equation : 

Ca3(P04)2+CaH4(P04)2=4CaHP04. 

The  result  is  a  phosphate  called  by  the  names  "re- 
turned," "reduced,"  "reverted,"  "precipitated."  Tri- 
calcium  or  bone  phosphate  is  insoluble  in  water,  and  di- 
calcium,  or  precipitated,  very  slowly  soluble.  Con- 
sequently, the  value  of  the  fertilizer  depends  chiefly  upon 
the  quantity  of  soluble  phosphate  present.  The  sample 
should  be  thoroughly  mixed  to  insure  that  the  portion 
taken  for  analysis  fairly  represents  the  average  quality. 

Commercial  superphosphate  of  lime  always  contains 
more  or  less  moisture,  which  may  vary  greatly  on  keeping 
the  sample.     To  avoid  error  from  this  source,  a  portion 


198  SUPERPHOSPHATE   OF   LIME. 

s 

should  be  taken  for  the  determination  of  moisture  (by- 
drying  1  gm.  at  100°  C,  until  it  ceases  to  lose  weight),  at 
the  same  time  that  portions  are  weighed  out  for  the  deter- 
mination of  the  other  constituents.  Some  chemists  prefer 
to  determine  the  moisture  on  a  larger  portion  of  the 
sample  as  received  (up  to  10  gms.  or  more)  and  then  to  dry 
half  a  pound  or  more  of  the  sample  on  the  water-bath, 
pulverizing  and  mixing  it  as  it  dries,  and  to  use  portions 
of  the  sample  thus  dried  for  determination  of  the  moisture 
left,  and  for  phosphoric  acid,  etc.  (Stillwell,  Proc,  Am. 
Chem.  Soc,  II.,  64.)  The  results  must  be  calculated  back 
so  as  to  show  the  composition  of  the  moist  sample  (as 
received). 

There  are  two  methods  of  determining  the  different  phos- 
phates present  in  a  fertilizer  usually  followed  by  chemists, 
as  follows  : 

First  Method. — Weigh  1  gm.  of  the  superphosphate, 
transfer  it  to  a  shallow  mortar,  rub  up  with  50  c.  c.  of  warm 
water  (of  a  temperature  of  about  60°  C),  and  pour  the 
turbid  fluid  on  a  filter  ;  then  add  50  c.  c.  more  warm  water, 
triturate  again,  and  pour  the  water  containing  the  finer 
particles  of  the  material  on  the  filter.  Repeat  this  treat- 
ment with  50  c.  c.  more  warm  water,  pour  all  the  contents 
of  the  mortar  on  the  filter,  and  wash  with  enough  warm 
water  to  make  the  volume  of  fluid  equal  to  200  c.  c.  There 
will  now  be  a  filtrate  containing  the  soluble  phosphoric 
acid,  and  a  residue  containing  the  insoluble  and  precipi- 
tated phosphoric  acid. 

Soluble  Phosphoric  Acid. — To  the  filtrate  containing 
the  soluble  phosphoric  acid  add  4  or  5  gms.  of  sodium 
nitrate,  and  the  same  quantity  of  sodium  carbonate,  evapo- 
rate to  dryness,  fuse  to  destroy  the  organic  matter  extracted 
by  the  water,  the  heat  of  an  open  Bunsen  burner  being 
sufficient,  remove  the  fused  mass  from  the  crucible  with 
hot  water,  boil,  and  filter,  if  necessary.  As  nearly  all  of 
the  phosphoric  acid  in  superphosphates  is  soluble,  and  is 
consequently  in  this  solution,  dilute  to  1  litre,  and  take 


PRECIPITATED   AND   INSOLUBLE   PHOSPHATE.  199 

200  c.  c,  or  one  fifth  of  it,  for  phosphoric  acid,  to  be 
determined  by  means  of  ammonium  molybdate. 

The  largest  amount  of  phosphoric  acid  that  can  be 
present  in  pure  bone  phosphate  is  less  than  46  per  cent. 
As  all,  however,  is  rarely  converted  into  soluble  phosphate, 
and  as  there  is  usually  a  large  amount  of  other  substances 
present,  it  may  be  safely  assumed  that  50  c.  c.  of  ammo- 
nium molybdate  solution,  1  c.  c.  of  which  will  precipitate 
1.3  milligrammes  of  phosphoric  acid,  is  sufficient  in  all  cases 
to  precipitate  the  soluble  phosphoric  acid  in  one  fifth  of 
a  gm.  of  superphosphate. 

Precipitated  Phosphoric  Acid. — Wash  the  residue  con- 
taining the  insoluble  and  precipitated  phosphoric  acid 
into  a  beaker,  add  a  solution  of  15  gms.  of  ammonium 
citrate  in  50  c.  c.  of  water  (equivalent  to  sp.  gr.  1.09),  warm 
at  a  temperature  of  60°  C.  for  three  quarters  of  an  hoar,  fil- 
ter and  wash  with  about  150  c.  c.  of  water  of  60°  C.  Treat 
the  filtrate  as  before  with  nitrate  and  carbonate  of  sodium 
(4  or  5  gms.  of  each),  evaporate  to  dryness,  fuse,  take  up 
with  water,  acidulate  with  nitric  acid,  boil,  filter  if  neces- 
sary, and,  as  the  amount  of  precipitated  phosphoric  acid  is 
small,  treat  the  whole  solution  with  about  25  c.  c.  of  am- 
monium molybdate  solution,  determining  the  phosphoric 
acid  as  usual. 

Insoluble  Phosphoric  Acid. — Fuse  the  residue  left  after 
extracting  the  soluble  and  precipitated  phosphoric  acid, 
with  sodium  nitrate  and  carbonate  (4  or  5  gms.  of  each), 
over  a  common  Bunsen  burner,  remove  the  mass  from  the 
crucible  with  water  and  nitric  acid,  boil,  and  filter  if  neces- 
sary. As  the  amount  of  insoluble  phosphate  is  small,  use 
all  the  solution  for  determining  the  phosphoric  acid.  Add 
to  the  solution  about  25  c.  c.  of  ammonium  molybdate  solu- 
tion, and  proceed  as  usual. 

Second  Method. — A  better  method  is  the  one  adopted 
by  a  committee  of  German  chemists  and  reported  by  Frese- 
nius,  one  of  the  number,  in  the  Zeit.  fur  Anal.  Chem., 
Vol.  VII,  p.  304.     See  also  Am.  Chem.,  October,  1871. 


200  SUPERPHOSPHATE  OF   LIME. 

Treat  1  gm.  with  water  alone,  as  directed  in  first  method, 
to  dissolve  out  the  soluble  phosphate,  and,  after  drying, 
fuse  the  residue  with  nitrate  and  carbonate  of  sodium 
(about  4  or  5  gms.  of  each),  dissolve  the  fused  mass 
with  water  and  nitric  acid,  and  treat  the  whole  solu- 
tion for  phosphoric  acid,  as  in  the  first  method, 
with  ammonium  molybdate.  This  will  give  the  insol- 
uble and  precipitated  phosphoric  acid.  At  the  same 
time,  treat  another  gm.  with  water  and  ammonium 
citrate,  as  in  the  first  method,  to  remove  the  solu- 
ble and  precipitated  phosphoric  acid,  and  fuse  the  dried 
residue  as  before.  As  the  insoluble  phosphoric  acid  is 
small  in  amount,  determine  it  in  the  whole  solution  as 
before. 

At  the  same  time  that  the  two  portions  are  being  treated 
for  insoluble  phosphoric  acid,  and  for  insoluble  and  pre- 
cipitated phosphoric  acid  (together),  fuse  another  gm.  of 
the  superphosphate  with  nitrate  and  carbonate  of  sodium 
(5  gms.  of  each),  bring  into  solution  with  water  and  nitric 
acid  as  before,  dilute  to  1  litre,  and  in  200  c.  c. ,  equivalent 
to  one  fifth  of  a  gm. ,  determine  the  total  phosphoric  acid. 

By  deducting,  from  the  amount  of  total,  the  amount  of 
insoluble  and  precipitated,  that  of  soluble  phosphoric  acid 
is  estimated. 

By  deducting,  from  the  amount  of  insoluble  and  precipi- 
tated, that  of  insoluble,  the  amount  of  precipitated  phos- 
phoric acid  is  estimated. 

In  £ases  where  iron  and  aluminum  are  not  present,  phos- 
phoric acid  may  be  determined  volumetrically,  by  means 
of  uranium,  with  sufficient  accuracy  for  determining  the 
value  of  superphosphate  for  fertilizing  purposes. 

Solutions  Required — A  solution  of  uranium  acetate. 
prepared  by  dissolving  about  34  gms.  in  1  litre  of  water. 

A  solution  of  10.085  gms.  of  pure  crystallized  liydro- 
disodium  phosphate  in  1  litre  of  water.  The  salt  should 
be  unefnoresced,  coarsely  powdered,  and  dried  by  pressing 
between  folds  of  bibulous  paper  before  weighing. 


VOLUMETRIC.  201 

A  solution  of  sodium  acetate,  prepared  by  dissolving 
100  gms.  of  sodium  acetate  in  water,  adding  100  c.  c.  of 
acetic  acid,  and  diluting  to  1  litre. 

A  solution  of  potassium  ferrocyanide. 

Uranium  Solution. — This  is  standardized  by  means  of 
the  sodium  phosphate  solution,  of  which  50  c.  c.  are  in- 
troduced into  a  beaker,  and  heated  to  about  100°  C.  on  a 
water-bath. 

After  adding  5  c.  c.  of  the  sodium  acetate  solution,  the 
uranium  solution  is  run  in  from  a  burette,  rapidly  up  to 
the  amount  of  15  c.  c,  and  then,  drop  by  drop  (testing  fre- 
quently by  placing  a  drop  of  the  sodium  phosphate  solu- 
tion on  a  white  porcelain  plate  and  adding  a  drop  of  the 
potassium  ferrocyanide  solution).  As  soon  as  the  uranium 
is  in  excess,  a  reddish-brown  coloration  appears.  The  so- 
lution is  then  heated  on  a  water-bath  for  a  few  minutes, 
and  the  test  repeated.  If  the  same  reaction  takes  place, 
the  titration  is  completed.  The  uranium  solution  should  be 
of  such  a  strength  that  20  c.  c.  of  it  are  equal  to  the  50  c.  c. 
of  rjhosphate  solution.  If  this  should  not  be  the  case,  as 
the  uranium  solution  is  purposely  made  too  strong,  dilute 
accordingly,  and  repeat  the  titration  on  another  portion  of 
the  phosphate  solution,  to  insure  correctness. 

Analysis. — This  is  made  under  conditions  as  nearly  sim- 
ilar as  possible  to  those  under  which  the  standardizing  was 
performed.  Add  to  the  fluid  to  be  examined,  5  c.  c.  of 
the  sodium  acetate  solution,  and  proceed  with  the  titration 
in  the  manner  directed  for  standardizing  the  uranium  solu- 
tion. 

As  1  c.  c.  of  the  uranium  solution  is  equivalent  to  0.005 
gm.  of  phosphoric  acid,  the  calculation  of  the  amount  in 
the  solution  under  examination  is  very  simple. 

Chlorine. — Digest  1  gm.  with  about  50  c.  c.  of  water, 
filter,  wash,  make  the  filtrate  alkaline  with  sodium  carbon- 
ate, add  a  little  sodium  nitrate,  evaporate  to  dryness,  fuse 
gently,  take  up  with  water,  and  determine  the  chlorine 
volumetrically  with  standard  silver  nitrate  solution. 


202  SUPEEPHOSPHATE   OF   LIME. 

Sulphuric  Acid. — Make  a  solution  of  1  gm.  as  for 
chlorine,  acidulate  with,  hydrochloric  acid,  and  determine 
the  sulphuric  acid  with  barium  chloride,  as  usual. 

Free  Sulphuric  Acid. — Make  an  aqueous  solution  of 
the  superphosphate  (1  or  2  gms.),  evaporate  slowly,  until 
only  a  small  quantity  is  left ;  add  about  7  volumes  of 
absolute  alcohol,  and  allow  to  settle  in  the  cold  for  some 
hours.  This  precipitates  all  sulphates,  and  leaves  in  solu- 
tion, besides  phosphates,  the  free  sulphuric  acid.  Filter, 
wash  with  alcohol,  add  a  large  amount  of  water  to  the  so- 
lution, carefully  evaporate  off  the  spirit,  and  estimate  the 
acid  in  the  solution  in  the  usual  manner  by  precipitation 
with  barium  chloride.     (Crookes's  Select  Methods,  p.  312.) 

Moisture. — Dry  1  gm.  to  constant  weight  at  a  tempera- 
ture of  100°  C. 

Ammonia. — See  analysis  of  guano. 

Alkalies. — Make  a  water  solution  of  2  or  3  gms.  of  the 
superphosphate,  and  determine  the  alkalies  as  in  the 
analysis  of  water. 

Ash. — Incinerate  4  or  5  gms.  of  the  superphosphate 
until  all  carbonaceous  matter  is  consumed,  cool,  and 
weigh.  If  the  ash  is  not  of  a  light  color,  and  free  from, 
all  black  specks,  repeat  the  ignition  and  weighing. 

For  a  method  of  making  an  exhaustive  analysis  of 
superphosphate,  consult  Fres.,  Quant.  Anal.,  §235. 


REPORTING  RESULTS. 

REPORT. 

Soluble  phosphoric  acid 

Precipitated  phosphoric  acid 

Total  available  phosphoric  acid  (P806)* 

Equivalent  to  bone  phosphate  [Ca3(P04)2]* 


Insoluble  phosphoric  acid 

Equivalent  to  bone  phosphate • 

Total  phosphoric  acid , 

Equivalent  to  bone  phosphate 

Nitrogen , 

Equivalentto  ammonia (NH3) 

Potash  (K20) 

Equivalent  to  potassium  sulphate  (K8S04). 

Soda(Na20) 

Equivalent  to  sodium  sulphate  (Na2S04). . , 
Water , 


*1  gm.  P205is  equivalent  to  2.1831  gms.  Ca3(P04)a,  as  will  be  found  by 
stoichiometrical  calculation.  The  factor  is  a  convenient  one  to  use  in  calculating 
results  in  this  analysis  or  in  that  of  guano. 


CHAPTER    XXXin. 

MILK. 

The  constituents  are  water,  sugar,  casein,  and  ash  01 
mineral  salts. 

Weigh  a  small  platinum  dish  ;  then  add  a  5-gm.  weight 
to  those  on  the  pan,  and  run  in  from  a  pipette  enough 
milk  to  weigh  a  few  milligrammes  over  5  gms.,  determine 
the  exact  weight  as  quickly  as  possible  and  proceed. 

Water. — Evaporate  over  a  water-bath,  until  the  milk 
solids  look  dry  ;  then  dry  in  an  air-bath  at  100°  to  105°  C. 
for  one  to  one  and  a  half  hours,  weigh,  and  dry  again,  for 
one  half  to  three  quarters  of  an  hour,  and  weigh  again. 
Repeat  this  treatment  until  the  loss  is  less  than  5  milli- 
grammes. 

Long  heating  should  be  avoided,  as  far  as  possible,  as 
the  sugar  is  apt  to  decompose  and  affect  the  results. 

Fat. — Weigh  a  small  beaker  and  have  ready  a  water- 
bath  full  of  boiling  water.  Pour  about  10  c.  c.  of  ether  on 
the  milk  solids,  allow  it  to  soak  into  the  solids  for  a  few 
minutes,  place  the  dish  on  the  water-bath,  and  keep  it 
there  until  the  ether  boils.  Then,  after  drying  the  bottom 
of  the  dish  with  bibulous  paper,  pour  the  ether  into  the 
weighed  beaker,  by  means  of  a  glass  rod.  If  the  milk 
solids  flake  off  from  the  dish  and  become  stirred  up  in  the 
ether,  a  little  care  will  suffice  to  prevent  their  being 
carried  over  into  the  beaker,  as  they  sink  rapidly  in  the 
ether.  Repeat  this  treatment  with  ether  about  6  times. 
Cover  the  beaker  with  a  piece  of  filter-paper,  and  evaporate 
off  the  ether  over  hot  water,  being  careful  to  have  no  flame 
near  the  beaker.  When  the  ether  is  all  gone,  dry  the 
beaker  in  an  air-bath  at  100°  to  105°  C,  for  about  15 
minutes.  The  residue  is  butter-fat.  Should  it  contain 
any  water,  this  should  be  driven  off  at  as  low  a  tempera* 


BUTTER — STTG  AE — SALTS .  205 

ture  as  possible,  that  is,  on  a  water-bath  rather  than  in  an 
air-bath.  The  milk  solids,  after  treatment  with  ether,  re- 
quire about  30  minutes'  drying  at  1 00°  to  105°  C.  after  the 
ether  is  all  gone.  When  water  is  present,  the  direct 
determination  gives  results  a  little  low,  as  the  expulsion  of 
the  water  appears  to  cause  some  decomposition  of  the 
butter,  making  the  color  dark,  and  giving  it  a  peculiar 
odor.  The  determination  by  direct  weight  of  the  butter 
and  that  by  loss  seldom  agree  exactly,  but  usually  within 
5  milligrammes  or  less. 

Sugar. — After  extracting  the  butter  and  expelling  the 
ether,  nearly  fill  the  dish  with  water,  place  it  on  a  boiling- 
water  bath,  leave  it  there  for  about  20  minutes,  pour  off 
the  water  into  a  previously  weighed  dish  of  similar  size, 
and  place  this  also  on  a  water-bath  to  evaporate.  Repeat 
this  treatment  with  water  4  or  5  times.  After  the  contents 
of  the  dishes  appear  dry,  leave  them  in  an  air-bath,  heated 
to  100°  C,  for  about  2  hours,  cool,  and  weigh  them.  If  the 
loss  and  direct  weight  agree,  further  drying  is  unnecessary  ; 
otherwise,  dry  and  weigh  again.  This  gives  the  sugar  and 
some  soluble  mineral  salts. 

Ash  of  Sugar. — Ignite  the  dish  containing  the  sugar  at 
as  low  a  temperature  as  possible,  to  avoid  the  loss  of  salts 
volatile  at  high  temperature,  such  as  potassium  chloride, 
etc.  The  residue  is  the  ash  of  sugar,  and  the  loss  by  ig- 
nition, sugar. 

Casein.  —After  extracting  the  sugar,  the  residue  left  in 
the  dish  is  casein,  and  some  insoluble  mineral  salts. 

Ash  of  Casein. — Ignite  the  dish  containing  the  casein, 
cool,  and  weigh.  The  residue  will  be  ash  of  casein,  and 
the  loss  by  ignition  casein. 

Ash  or  Mineral  Salts. — Combine  the  weights  of  ash  ol 
sugar  and  ash  of  casein.  The  sum  will  be  the  ash  or 
mineral  salts. 

For  most  purposes,  the  determination  of  water  and 
butter  is  sufficient,  giving  water,  butter,  and  solids,  not 
fat. 


206  MILK. 

The  British  Society  of  Public  Analysts  fixes  on  maximum 
water  as  88.5  per  cent,  and  minimum  butter  as  2,5  per 
cent,  and  solids,  not  fat,  as  9  per  cent.  (Qhem,  News*, 
XXXI.,  p.  58,  1875.) 


CHAPTER    XXXIV. 

ACIDIMETRY   AND   ALKALIMETRY. 

The  solutions  usually  employed  are  of  sulphuric  acid, 
hydrochloric  acid,  oxalic  acid,  sodium  or  potassium  hy- 
drate, and  also  of  some  substance  which  is  colored  differ- 
ently by  acids  and  alkalies,  such  as  litmus,  cochineal, 
coralline,  logwood,  etc. 

A  solution  is  styled  normal  when  the  molecular  weight 
of  the  substance  is  the  same  as  the  number  of  milli- 
grammes of  it  in  1  c.  c.  of  the  solution. 

Half-Normal  Sulphuric  Acid. — This  solution  is  pre- 
pared so  as  to  contain  0.049  gm.  H2S04,  or  0.040  gm.  S03, 
in  each  c.  c.  To  600  c.  c.  of  water  add  about  20  c.  c.  of 
chemically  pure  concentrated  sulphuric  acid,  mix  well, 
and  allow  to  cool.  Measure  out  from  the  burette  two  por- 
tions of  exactly  20  c.  c,  add  to  each  portion  50  c.  c.  of  hot 
water,  and  40  c.  c.  of  a  saturated  solution  of  barium 
chloride.  Treat  the  precipitates  of  barium  sulphate,  and 
determine  the  sulphuric  acid.  If  the  precipitates  do 
not  differ  in  weight  more  than  0.010  gm.,  take  the  average, 
calculate  the  sulphuric  acid  in  1  c.  c.  of  the  solution  and 
dilute,  as  directed  afterward. 

Another  method  is  as  follows  : 

Introduce  about  3  gms.  of  dry  C.  P.  sodium  carbonate 
into  a  weighed  platinum  dish,  heat  to  180°  C  ,  or  just  be- 
low redness,  for  a  few  minutes,  cool,  and  weigh,  repeating 
to  constant  weight.  This  gives  the  weight  of  the  sodium 
carbonate.  Then  add  to  the  contents  of  the  dish  about 
30  c.  c.  of  water,  warm  until  the  sodium  carbonate  is  dis- 
solved, run  in  from  a  burette  20  c.  c.  of  the  sulphuric  acid 
solution,  keeping  the  dish  covered  while  doing  so,  heat  on 
a  water-bath,  with  the  cover  on,  until  all  free  carbonic  acid 
is  expelled ;  then  remove  the  cover,  after  washing  it  and 


208  ACIDIMETRY  AND   ALKALIMETRY. 

allowing  the  washings  to  run  into  the  dish,  continue  the 
evaporation  to  perfect  dryness,  heat,  as  in  the  first 
instance,  to  constant  weight,  either  in  an  air-bath  at  180° 
C,  which  is  the  better  plan,  or  over  an  open  flame,  at  a 
heat  just  below  redness.  The  increase  in  weight  is  propor- 
tional to  the  amount  of  sulphuric  acid  used,  so  long  as 
there  is  an  excess  of  sodium  carbonate  over  acid. 

The  calculation  of  the  value  of  the  solution  is  made  by 
the  following  proportion :  The  difference  between  the 
molecular  weights  of  sulphuric  acid  and  carbonic  acid 
(36)  is  to  the  molecular  weight  of  sulphuric  acid  (98)  as 
the  difference  in  the  weights  of  dish  and  contents,  before 
and  after  adding  sulphuric  acid,  is  to  the  weight  of  sul- 
phuric acid  used,  and  as  20  c.  c.  of  sulphuric  acid  were 
used,  this  result  divided  by  20  will  give  the  value  of  1  c.  c. 
of  the  acid. 

It  is  customary  to  calculate  the  result  in  terms  of  S03 
instead  of  H2S04.  Suppose  it  is  found  by  the  experiment, 
that  1  c.  c.  of  the  solution  contains  0.044  gm.  of  S03  instead 
of  0.040  gm.,  and,  consequently,  100c.  c.  contain 4.400 gms. 
instead  of  4  gms.,  then  as  4  gms.  are  to  100  c.  c.  so  are  4.4 
gms.  110  c.  c.  Therefore,  10  c.  c.  of  water  must  be  added 
to  each  100  c.  c.  of  the  acid  solution.  To  do  this,  fill  a  dry 
500  c.  c.  flask  to  the  holding  mark  with  the  acid  solution, 
pour  it  into  a  clean  dry  bottle,  introduce  into  the  flask  50 
c.  c.  of  water,  and  pour  this  also  into  the  bottle,  after 
shaking  well,  pour  the  fluid  back  into  the  flask,  and 
finally  into  the  bottle  for  use.  This  is  done  to  mix  the 
fluid  thoroughly.  The  bottle  should  be  kept  corked. 
This  is  what  is  called  half -normal  sulphuric  acid  solution, 
1  c.  c.  of  which  contains  49  milligrammes  of  HsS04,  or  40 
milligrammes  of  S03. 

A  solution  of  sodium  carbonate  may  be  used  to  obtain 
the  solution  of  half  normal  sulphuric  acid,  thus  :  Heat  a 
moderate  amount  of  pure  dry  sodium  carbonate  in  a  plat- 
inum dish,  until  it  begins  to  sinter  together.  Transfer, 
while  hot,  to  a  dry  specimen  tube  or  flask  ;  cork  it  up  and 


STANDARDIZING.  209 

allow  the  salt  to  cool  out  of  contact  with  the  air.  With 
this  material  make  a  half  normal  solution  (53  grammes 
in  1  litre,  or  26.5  grammes  in  500  c.  c,  etc.).  Mix  the 
solution  well  and  place  some  in  a  burette.  Do  the 
-same  for  the  sulphuric  acid  solution  made  as  first  de- 
scribed. Run  10  c.  c.  of  the  sodium  carbonate  solu- 
tion into  a  beaker,  add  to  it  10  c.  c.  of  the  sulphuric 
acid,  or  enough  to  render  it  acid,  and  boil  to  expel 
the  carbon  dioxide,  which  would  otherwise  affect  the 
indicator  and  thus  interfere.  Then  add  a  few  drops 
of  the  indicator  (cochineal  is  preferable  in  this  case) 
and  run  in  the  sodium  carbonate  solution  until  the 
color  shows  that  the  solution  is  neutral.  From  the 
data  thus  obtained,  calculate  the  amount  of  dilution  re- 
quired for  the  sulphuric  acid  ;  e.  g.,  suppose  10  c.  c.  so- 
dium carbonate  solution  were  used  at  first — then  10  c.  c. 
sulphuric  acid,  and  finally,  after  boiling,  2.3  c.  c.  sodium 
carbonate  to  effect  neutrality,  as  shown  by  the  color 
imparted  by  the  indicator.  Then  10  c.  c.  of  the  sulphuric 
acid  neutralizes  (10  -f-  2.3)  12.3  c.  c.  sodium  carbonate 
solution.  But  the  sulphuric  acid  should  be  half  normal, 
or  neutralize  the  sodium  carbonate  c.  c.  for  c.  c.  There- 
fore 12.3  c.  c.  sulphuric  acid  ought  to  have  been  used  if 
the  solution  was  of  the  right  strength  ;  or,  every  100  c.  c. 
of  the  acid  solution  should  be  diluted  to  123  c.  c. 

Measure  the  amount  of  the  diluted  acid  on  hand,  dilute 
in  the  proportion  indicated,  rinse  out  the  burette,  mix  well, 
and  repeat  the  test  in  the  same  way,  diluting  again  if 
necessary,  until  the  solutions  correspond  exactly.  The 
accuracy  of  the  sulphuric  acid  solution  should  finally  be 
verified  gravimetrically  by  precipitation  with  barium 
chloride  solution,  etc. 

Normal  Potassium  Hydrate. — This  solution  is  pre- 
pared so  as  to  contain  0.05t)l  gin.  of  potassium  hydrate, 
(KHO)  or  0.0471  gm.  of  potassium  oxide  (K20.) 

Dissolve  about  20  gms.  of  potassium  hydrate  in  300  c.  c. 
of  water,  and  when  dissolved  fill  a  Mohr  burette  with  the 


210  ACIDIMETRY   AND    ALKALIMETRY. 

solution  to  the  zero  mark,  and  run  it,  drop  by  drop,  inta 
a  beaker  containing  10  c.  c.  of  the  standardized  sulphuric 
acid  diluted  to  200  c.  c,  and  also  a  little  cochineal  solu- 
tion. Continue  to  add  the  alkaline  solution  until  the 
yellow  color,  which  is  the  color  produced  upon  cochineal 
by  acid,  becomes  carmine,  showing  that  the  fluid  has 
become  alkaline.  Kepeat  upon  different  quantities  of 
acid.  The  color  imparted  to  any  number  of  c.  c.  of  the 
sulphuric  acid  solution,  by  the  cochineal,  should  change 
upon  the  addition  of  exactly  the  same  quantity  of  alka- 
line solution.  If  it  does  not,  the  potassium  hydrate  solu- 
tion must  be  diluted  until  the  two  solutions  agree.  Sup- 
pose it  is  found  by  experiment  that  10  c.  c.  of  the  acid  so- 
lution requires  only  8  c.  c.  of  the  alkaline,  then,  to  every 
8  c.  c,  2  c.  c.  of  water  must  be  added,  or  to  each  100  c.  c. 
of  solution  25  c.  c.  of  water.  Employ  the  same  method  of 
diluting  and  mixing  as  in  the  case  of  standard  sulphuric 
acid.  Now,  if  1  c.  c.  of  the  solution  of  potassium  hydrate 
exactly  neutralizes  1  c.  c.  of  the  solution  of  sulphuric 
acid,  the  quantity  of  K20  and  S03  must  be  exactly  in  pro- 
portion to  their  molecular  weighty  and  as  each  c.  c.  of  the 
acid  solution  was  found  to  contain  0.040  gm.  of  SOs> 
each  c.  c.  of  the  alkaline  solution  must  contain  0.0471  gms. 
of  K20,  as  80  parts  of  S03  are  neutralized  by  94.2  parts  of 
K20,  or  0.040  gm.  of  S03  by  0.0471  gm.  of  K20.  It  is  some- 
times convenient  to  use  potash  lye  of  unknown  strength 
for  the  preparation  of  the  standard  alkaline  solution,  in 
which  case  the  quantity  of  alkali  in  a  given  volume  can  be 
determined  approximately  by  finding  the  specific  gravity 
of  the  lye  with  a  hydrometer,  and  calculating  the  per  cent 
of  alkali  by  reference  to  the  table  in  the  Appendix,  which 
gives  the  per  cent  of  K20  in  solutions  of  different  specific 
gravities. 

Indicators. — The  coloring  matters  used  to  show  when 
the  fluid  is  acid  or  alkaline  are  so  called.  Although  a 
great  many  have  been  prepared,  only  a  few  are  in  common 
use  : 


INDICATORS.  211 

Litmus  :  To  prepare  this,  Sutton  directs  to  boil  the  lit- 
mus, reduced  to  coarse  powder,  two  or  three  times  with 
alcohol  of  about  80  per  cent,  and  throw  the  liquid  so 
obtained  away.  Then  digest  the  litmus  repeatedly  with 
cold  water  until  all  soluble  color  is  extracted,  let  the  mixed 
washings  settle  clear,  decant,  and  add  to  them  a  few  drops 
of  concentrated  sulphuric  acid  until  quite  red,  then  heat 
to  boiling  ;  this  will  decompose  the  alkaline  carbonates 
and  convert  them  into  sulphates.  Now  cautiously  add 
baryta  water  until  the  color  is  restored  to  blue  or  violet, 
let  the  barium  sulphate  settle  perfectly,  and  decant  into  a 
proper  vessel  for  use.  The  solution  must  be  kept  in  an 
open  bott]e,  as  it  loses  color  in  a  closed  vessel,  although 
it  will  recover  it  upon  exposure.  Litmus  cannot  be  used 
in  the  presence  of  carbonic  acid ;  consequently,  the  standard 
alkali,  if  litmus  is  used  as  the  indicator,  must  be  entirely 
free  from  it. 

Cochineal :  Macerate,  with  frequent  shaking,  about  3 
gms.  of  good  cochineal  (in  powder)  with  250  c.  c.  of  a  mix- 
ture of  3  or  4  volumes  of  distilled  water,  and  1  volume  of 
alcohol,  and  filter  through  Swedish  paper.  It  keeps  well 
inclosed  bottles.  It  cannot  be  used  in  the  presence  of 
salts  of  iron,  but  is  not  affected  by  carbonic  acid — at  least, 
in  moderate  quantity. 

Logwood  :  Boil  down  a  few  shavings  from  the  interior 
of  a  piece  of  logwood  with  distilled  water,  and  mix  the 
concentrated  decoction  with  1  to  2  volumes  of  alcohol.  It 
must  be  kept  unexposed  to  light.  It  cannot  be  used  in 
presence  of  oxides  of  the  heavy  metals. 

Coralline:  An  alcoholic  solution  of  this  is  extremely 
sensitive,  and  rapid  as  an  indicator,  and  is  particularly 
well  adapted  to  the  titration  of  vinegar  and  organic  acids 
generally. 

Normal  Hydrochloric  Acid. — Mix  500  c.  c.  of  water 
with  100  c.  c.  of  pure  hydrochloric  acid  of  1.12  sp.  gr.,  run 
out  from  a  burette  2  portions  of  exactly  20  c.  c.  each,  and 
determine  the  amount  of  hydrochloric  acid  in  each,  with 


212  ACIDIMETRY   AND    ALKALIMETRY. 

silver  nitrate,  as  directed  in  the  analysis  of  barium  chloride. 
If  the  two  results  agree  closely,  take  the  mean,  calculate 
the  amount  of  water  necessary  to  make  the  solution  of 
such  a  strength  that  1  c.  c.  will  contain  0.03646  gm.  of 
hydrochloric  acid.  If  a  normal  solution  of  potassium 
hydrate  is  at  hand,  also  test  a  portion  of  the  solution  with 
it.     The  solutions  should  agree. 

Half-Normal  Oxalic  Acid. — Dissolve  63  gms.  of  pure 
crystallized  oxalic  acid  in  1  litre  of  water  and  standardize 
the  solution  by  titrating  a  portion  of  it  with  standardized 
potassium  hydrate  solution,  or  standardized  potassium 
permanganate  solution. 

These  standard  solutions  may  be  kept  in  well-closed  bot- 
tles for  some  time  without  appreciable  change.  Glass- 
stoppered  bottles  should  be  used  for  the  acid  solutions. 
The  bottles  containing  the  alkaline  solutions  should  be 
closed  with  tightly-fitting  corks  which  have  been  dip- 
ped in  melted  paraffine. 

These  standard  alkalimetric  and  acidimetric  solutions 
find  application  in  many  of  the  processes  of  quantitative 
analysis,  which  it  would  be  here  unnecessary  to  specify. 
As  samples  of  their  application  we  will  take  the  titration 
of  crude  sodium  carbonate  and  the  determination  of  the 
acidity  of  vinegar. 

Crude  Sodium  Carbonate. — Weigh  out  5.3  gms.  of  the 
sample  (=  one  twentieth  of  an  equivalent  of  JSra2C03),  dis- 
solve in  a  little  hot  water,  filter,  and  wash  the  residue, 
bringing  the  bulk  of  filtrate  and  washings  up  to  100  c.  c. 
Thoroughly  mix  this  solution  by  pouring  it  backward  and 
forward  a  few  times  from  the  flask  to  the  beaker.  Then 
take  10  c.  c.  of  the  solution,  run  in  10  c.  c.  of  the  half- 
normal  sulphuric  acid  solution,  dilute  with  about  40  c.  c. 
of  water,  boil  to  expel  excess  of  carbonic  acid,  add  a  few 
drops  of  cochineal,  and  then  run  into  it  normal  potassic 
hydrate  solution  until  the  solution  is  exactly  neutral. 
Repeat  the  operation  with  2  or  3  other  portions  of  10  c.  c. 
each,  and  take  the  average.     The  number  of  c.  c.  of  sul- 


VINEGAK.  213 

phuric  acid  solution  which  have  been  neutralized  by  the 
solution  of  the  sample,  multiplied  by  10,  give  at  once  the 
percentage  of  Na^COa  present  in  the  sample,  since  one 
twentieth  of  an  equivalent  of  that  compound  was  taken, 
and  half -normal  acid  was  used.  We  might  have  taken  a 
round  5  gms.,  but  in  that  case  an  unnecessary  elabo- 
ration is  introduced  into  the  calculation. 

This  method  of  weighing  out  one  tenth  or  one  twentieth 
of  an  equivalent  in  gms.  of  a  substance,  dissolving  to  100 
c.  c,  and  titering  portions  thereof,  is  usually  the  most 
convenient  mode  of  procedure.  In  some  cases,  it  may  be 
convenient  to  make  a  one-twentieth  normal  solution  of  sul- 
phuric acid,  or  of  potassium  hydrate  to  correspond. 

For  vinegar,  weigh  out  in  a  stoppered  flask  60  gms.  of 
the  vinegar,  dilute  to  1000  c.  c.  (or  30  gms.,  and  dilute  to 
500  c.  a),  mix  thoroughly,  and  take  100  c.  c.  at  a  time  for 
titration  with  the  potassium  hydrate  solution.  In  this  case, 
it  is  best  to  use  coralline  as  an  indicator,  since  the  cochi- 
neal does  not  show  a  sufficiently  marked  deviation  from  the 
neutral  tint,  when  only  small  amounts  of  free  acetic  acid 
are  present.  The  number  of  c.  c.  of  potassium  hydrate 
solution  required  just  to  give  a  full  alkaline*  color,  show 
the  percentage  of  acetic  acid  present,  since  in  this  case  an 
equivalent  of  acetic  acid  was  weighed  out,  the  percentage 
of  acetic  acid  being  usually  small  (about  3  to  10  per  cent). 

In  commerce,  vinegars  are  often  spoken  of  as  "  twenty 
grain,"  "  thirty  grain,"  "  forty  grain,"  etc.  This  means 
that  one  Troy  ounce  of  the  vinegar  will  exactly  neutralize 
20,  30,  40,  etc.,  grains  of  potassium  bicarbonate  (KHC03), 
and  usually  dealers  desire  to  have  the  results  expressed 
in  this  form.  In  such  cases,  it  is  easy  to  calculate,  from 
the  figures  obtained,  the  number  of  grains  of  potassium 
hydrogen  carbonate  (bicarbonate)  necessary  to  neutralize 
a  Troy  ounce  by  multiplying  the  percentage  obtained  by 
8.008.  The  reason  for  employing  this  factor  is  that  there 
are  480  grains  in  a  Troy  ounce,  and  the  number  of  grains 

*  Neutral  alkaline  acetates  have  a  slight  alkaline  reaction. 


214  ACLDIMETRY   AND    ALKALIMETRY. 

of  KHCO3  necessary  to  neutralize  480  grains  of  pure  acetic 
acid  is  found  to  be  800.8  by  the  following  proportion  : 
(HC2H302 :  KHCO3  =)60  :  100.1=480  :  800.8. 

The  decimal  place  is  changed  two  points  in  the  factor 
because  the  figure  expressing  percentage  is  100  times  too 
great,  being  expressed  as  a  whole  number,  instead  of  what 
it  really  is,  parts  in  100.  Suppose,  for  instance,  the  per- 
centage found  to  be  6.5  ;  then  6.5  X  8.008  =  52.052  grains 
of  KHCO3  required  to  neutralize  one  Troy  ounce.  It  is 
always  best  to  verify  the  result  by  weighing  out  a  Troy 
ounce  (31.100  gms.),  adding  to  it  an  amount  of  potassium 
hydrogen  carbonate  corresponding  to  the  number  of 
grains  found  (having  determined  the  strength  thereof  by 
titration  beforehand),  boiling  and  testing  the  reaction  of 
the  solution,  which  should  be  just  alkaline.  If  it  is  not, 
the  test  must  be  repeated. 

On  account  of  the  strong  color  of  some  vinegars,  which 
prevents  one  from  seeing  the  change  of  color  in  the  in- 
dicator, some  analysts  prefer  to  distill  the  acetic  acid  off, 
and  obtain  a  clear  solution  for  titration  (md.  Blyth, 
Manual  of  Practical  Chem.,  p.  210.)  Of  course,  when  it 
is  desirable  to  know  only  the  weight  of  acid  in  a  given 
bulk  of  solution,  as  number  of  ounces  in  1  gallon,  the  acid 
may  be  measured  out,  and  diluted  to  any  convenient 
strength,  and  aliquot  portions  taken  for  titration. 


CHAPTER    XXXV. 

COMMERCIAL   BICARBONATE   OF   SODA. 

WaHOOz. 

Moisture. — Weigh  out  1  gm.  in  a  platinum  boat,  and 
place  the  boat  and  contents  in  the  centre  of  a  piece  of  hard 
glass  tubing  about  8  or  10  inches  long.  Connect  the  tub- 
ing at  one  end,  by  means  of  a  tightly-fitting  tube  and  cork, 
with  a  bottle  containing  concentrated  sulphuric  acid  to  dry 
the  air  drawn  through  it,  and  at  the  other  end  with  a  cal- 
cium chloride  tube,  previously  weighed  and  prepared  by 
passing  C02  through  it  as  previously  described.  (Lime- 
stone, p.  59  ;  Elementary  Analysis  of  Sugar,  p.  230.)  The 
point  of  the  calcium  chloride  tube  should  be  passed 
through  the  cork,  as  a  connection  of  rubber  tubing  is  very 
likely  to  condense  the  water  driven  off,  which  is  drawn 
into  the  tube  then  only  with  difficulty.  The  other  end  of 
the  calcium  chloride  tube  is  then  connected  with  an 
aspirator.  Start  the  aspirator,  and  then  apply  the  heat  of 
a  Bunsen  lamp  to  the  tubing  where  the  boat  lies.  Raise 
the  heat  steadily  until  the  tube  about  it  is  red  hot.  Keep 
it  at  that  temperature  for  fifteen  minutes  or  more.  Then 
withdraw  the  heat  and  allow  it  to  cool,  still  keeping  the 
aspirator  at  work,  until  the  tubing  and  calcium  chloride 
tube  are  cool.  Weigh  the  calcium  chloride  tube.  The  in- 
crease in  weight  is  the  moisture  present  in  the  sample. 
Withdraw  the  boat,  and  weigh  it  with  its  contents.  The 
loss  represents  water  plus  half  the  carbon  dioxide.  This 
should  be  one  half  the  amount  of  the  carbon  dioxide  as 
determined  afterward. 

Carbon  Dioxide. — Introduce  0.5  gm.  into  the  flask  of  a 
carbon  dioxide  apparatus,  and  25  c.  c.  water  containing  2 
c.  c.  concentrated  sulphuric  acid,  or  5  c.  c.  concentrated 
nitric  acid,  and  determine  the  C02  as  usual  in  carbonates, 


216  COMMERCIAL    BICAKBONATE    OF   SODA. 

by  absorption  in  a  tube  of  soda-lime,  etc.     (See  Limestone, 
p.  59.) 

Hygroscopic  Moisture. — Dry  1  or  2  gms.  in  the  air-bath, 
at  100°  C.  to  constant  weight.  The  loss  represents  hygro- 
scopic moisture.  This,  deducted  from  total  water  deter- 
mined as  above,  gives  water  due  to  NaHC03.  Also,  from 
the  percentage  of  C02  calculate  the  water  due  to  ]NaHC03. 
These  two  results  should  agree — 

2NaHC03=Na20+H20+2C02. 

Soda  Combined  as  Carbonate. — Dissolve  1  gm.  in  about 
100  c.  c.  of  water,  add  cochineal  solution,  and  then  run  in 
from  a  burette  an  excess  of  standard  sulphuric  acid  solu- 
tion. (Alkalimetry,  p.  207.)  Boil  out  the  carbon  dioxide, 
and  titre  back  with  standard  potash  solution,  and  from 
these  results  calculate  the  amount  of  JSTa20  combined  as 
carbonate. 

Chloride. — Dissolve  1  gm.  in  100  c.  c.  of  water,  just  neu- 
tralize with  HJST03,  add  a  few  drops  of  saturated  solution 
of  potassium  chromate,  (1 :  5)  and  titre  with  standard  solu- 
tion of  silver  nitrate.  The  silver  nitrate  solution  is  made 
by  dissolving  17  gms.  pure  crystallized  AgN03  in  one  litre 
of  water.  It  is  standardized  by  testing  it  upon  a  solution 
of  pure  fused  sodium  chloride*  containing  1  gm.  in 
250  c.  c.  of  water.  The  potassium  chromate  is  used  as  an 
indicator,  since  the  red  silver  chromate  cannot  form  (per- 
manently) until  all  of  the  chloride  has  been  precipitated. 
The  silver  solution  is,  therefore,  added  until  the  liquid  has 
a  reddish  tinge,  which  cannot  be  removed  by  vigorous 
stirring. 

Sulphate. — Dissolve  3  or  4  gms.  in  water,  acidulate 
slightly  with  hydrochloric  acid,  boil  out  the  carbon  di- 
oxide, and  determine  S03  as  usual  with  BaCl2. 

Calculation :     Calculate    the    CI  to  ISTaCl,    the  SOs  to 

♦Most  conveniently  prepared  by  neutralizing  pure  sodium  carbonate  with 
hydrochloric  i  Ad,  evaporating  to  dryness  and  fusing.  All  ordinary  salt  (table 
salt)  contains  small  amounts  of  sulphates,  chiefly  calcium  and  magnesium,  and 
other  impurities,  which  cannot  be  separated  without  some  trouble. — E.  W. 


OALOULATION.  217 

.Na3S04 '  The  Na20  found  by  alkalimetrical  titration  repre- 
sents that  combined  as  carbonate — mono  or  bi — since  the 
neutral  NaCl  and  Na2S04  have  no  effect. 

For  calculating  the  amount  of  mono-  and  bicarbonate 

present  let  us  take  an  example.     Suppose  we  have  found 

in  a  sample  : 

Total  C02,  50.462  per  cent;  total  Na20,  37.894  per  cent. 

First  calculate    the    soda   to    C02   for   monocarbonate 

(Na20+C02  =  Na2C03)— A; 

then,  (]STa20  :  C02  =)  62  :  44  =37.894  :  x, 
xx  =  26.892  C02. 
By  subtracting  this  from  the  total  C02  we  obtain  the 
excess  of  C02  due  to  bicarbonate,  50.462  —  26.892  =  23.570 
C02.     This  represents  just  half  of  the  C02  of  the  bicarbon- 
ate, since  2NaHC03  =  (Na20+C02)+(H20+C02)— £. 

By  doubling  it,  then,  we  get  the  whole  amount  of  C03 
due  to  bicarbonate  present  in  the  sample. 
2X23.570  =  47.140  C02. 
Calculate  this  to  bicarbonate  : 

(C02 :  NaHCOg  =)  44  :  84  =  47.140 :  x2. 
x2  =  89.995  per  cent  bicarbonate  present. 
Calculate  it  also  to  Na20.    In  the  formula  B,  given  above, 
2C02  balance  one  Na30  ;  therefore, 

(2C02 :  Na20=)  88  :  62  =  47.14  :  x3. 
x3  =  33.212  Na20  in  bicarbonate. 
The  remainder   of   the  Na20  found  (37.894—33.212  = 
4.682)  is  present  as  monocarbonate. 
Calculate  accordingly : 

(NagO :  Na2COs  =)  62  :  106  =  4.682  :  xk 
x±  =  8.004  per  cent  of  monocarbonate  present. 
To  verify  the  calculation  : 

C02  due  to  bicarbonate  (x2) 47.140  per  cent 

C02  due  to  monocarbonate  (a?4  —  4.682) 3.322    "     " 


Total  COa 50.462    «« 


u 


CHAPTER    XXXVI. 

CHLOEIMETRY. 

Bleaching  powder,  commercially  known  as  chloride  of 
lime,  consists  of  a  mixture,  according  to  some  a  combina- 
tion, of  calcinm  hypochlorite,  CaCl202  and  calcium 
chloride,  CaCl2.  Its  value  depends  upon  the  amount  of 
chlorine  set  free  when  an  acid  is  added,  known  as  "  avail- 
able chlorine,"  e.  g.  : 

Ca(C10)2,CaCl2  +  2H2S04  =  2CaS04  +  2H20  +  Cl4. 
Ca(C10)2,CaCl2  +  4HC1  =  2CaCl2  +  2H20  +  Cl4. 

The  available  chlorine  of  bleaching  powder  is  two 
atoms  of  CI  for  each  atom  of  O  in  the  hypochlorite,  or,  as 
the  formula  indicates,  02  and  CU. 

The  compounds  known  commercially  as  chloride  of  soda 
(Labarraque's  solution)  and  chloride  of  potash  (Javelle 
water)  are  similar  in  composition  (NaG10,NaCl)  and 
(KC10,KC1),  and  are  the  same  as  regards  the  ratio  of  O 
and  CI. 

u  Iodized  Starch"  Paper. — Rub  up  in  a  mortar  3  gms. 
starch  with  50  c.  c.  warm  water,  wash  the  creamy  mixture 
into  a  beaker  containing  about  200  c.  c.  boiling  water, 
stirring  well  until  solution  is  effected.  Now  add  a  solu- 
tion of  1  gm.  KI  and  1  gm.  pure  Na2C03,  and  dilute  to 
half  a  litre.  Moisten  strips  of  filter-paper  with  this  solu- 
tion, and  dry  them  for  use,  keeping  them  in  a  corked  or 
stoppered  bottle. 

Arsenious  Acid  Solution. — Weigh  out  4.95  gms.  pure 
pulverized  white  arsenic  (As203),  transfer  to  a  litre  flask 
add  about  25  gms.  pure  crystallized  sodium  carbonate, 
and  200  c.  c.  water.  Boil  gently,  with  frequent  shaking 
until  all  is  dissolved,  cool,  and  dilute  up  to  the  litre 


ARSENIC    METHOD.  219 

mark.     One  c.  c.  of  this  solution  corresponds  to  0.00355 
available  CI,  as  may  be  seen  from  the  following : 
As203  +  CaCl202,CaCl2  =  As205  +  2CaCl2. 
The  four  atoms  of  available  chlorine  in  the  bleaching 
powder  correspond  to  the  two  atoms  of  O  taken  up  by  the 

As203. 

Molecular  weight  of  As203  =  198 
Molecular    weight  of    Cl4  =  142. 
Since  1  c.  c.  of  the  arsenious  solution  contains 

4.950  gms.  taken 

0.00495  gm.  As203  = — ;  then, 

6  1000  c.  c.  in  1  litre  ' 

198  :  142  =  0.00495 : 0.00355. 

Analysis. — Weigh  out  10  gms.  of  the  bleaching  powder, 
transfer  to  a  mortar,  add  50  or  60  c.  c.  of  water,  and  rub  to 
a  cream.  Allow  the  heavier  particles  to  subside,  decant 
the  turbid  supernatant  fluid,  add  more  water,  rub  up 
again,  and  continue  thus  until  all  the  powder  has  been 
transferred  to  a  litre  flask.  Fill  the  flask  up  to  the  mark, 
pour  the  contents  into  a  beaker,  mix  it  well,  and  take 
out  50  c.  c.  at  a  time  for  the  analysis.  The  solution  will 
always  remain  turbid,  but  this  cannot  be  avoided,  and  does 
not  interfere  with  the  accuracy  of  the  results,  provided  it 
is  uniformly  mixed.  Into  the  50  c.  c.  taken,  run  the 
arsenious  solution,  from  a  burette,  until  a  drop  of  the 
solution  taken  out  on  a  rod  no  longer  produces  a  blue  spot 
on  the  iodized  starch  paper,  which  has  been  previously 
moistened  and  spread  out  upon  a  white  plate. 

The  calculation  is  readily  made.  Fifty  c.  c.  of  bleaching 
powder  solution,  made  in  the  way  described,  is  equivalent 
to  0.5  gm.  Suppose  this  takes  45  c.  c.  of  the  arsenious  so- 
lution. Since  1  c.  c.  arsenious  sol.  =  0. 00355  gm.  available 
CI,  45  c.  c.  =  (45  X  0.00355)  =  0.15975  gm.  available  CI. 

If  then  0.5  gm.  bleaching  powder  =  0.15976  gm.  CI, 
lgm.  ==  0.3195    gm., 

or  the  bleaching  powder  contains  31.95  per  cent   of  avail- 
able chlorine. 


220  CHLORIMETRY. 

CHLORIMETRY   (IRON   METHOD). 

Weigh  out  10  gms.  bleaching  powder,  place  in  a  mortar, 
add  50  or  60  c.  c.  water,  rub  to  a  cream,  allow  the  coarser 
particles  to  settle,  pour  off  the  turbid  supernatant  fluid 
into  a  litre  flask,  add  more  water,  rub  again,  etc. ,  until  all 
the  powder  has  been  transferred  to  the  flask,  fill  up  to  the 
mark,  pour  the  solution  into  a  beaker,  and  mix  well ;  take 
out  50  c.  c.  for  the  analysis. 

Weigh  out  in  the  meantime  0.325  gm.  piano-forte  wire 
(=  0.324  gm.  Fe)  and  dissolve  it  in  2  c.  c.  cone.  H2S04 
diluted  with  10  c.  c.  water  in  a  small  valved  flask.  Cool, 
fill  the  flask  with  cold  water,  and  pour  into  a  large  beaker. 
ISTow  add  50  c.  c.  of  the  turbid  bleaching  powder  solution, 
pouring  it  in  slowly,  stirring  all  the  time.  Dilute  to  about 
500  c.  c.  Then,  by  means  of  a  standardized  solution  of  po- 
tassium permanganate  (prepared  as  described  under  Am- 
monio  Ferric  Sulphate,  p.  42),  determine  the  amount  oi 
iron  still  remaining  in  the  ferrous  form. 

The  reaction  is  : 

4FeS04+Ca(C10)2,CaCl2+2H2S04 
=  2Fe2(S04)3+2CaCl2+2H20  ; 
or  four  atoms  Fe  correspond  to  four  atoms  CI,  56  parts  Fe 
equivalent  to  35.5  parts  CI. 

The  mode  of  calculating  results  is  best  shown  by  example. 

Suppose  1  c.  c.  of  the  permanganate  was  equivalent  to 
0.003  gm.  Fe,  and  that  it  took  23.8  c.  c.  of  that  solution  to 
oxidize  the  ferrous  iron  not  acted  upon  by  the  bleach- 
ing powder  used,  in  an  amount  equivalent  to  0.5  gm. 
23.8  c.  c.  permanganate  correspond  to  (23.8  X  0,003)  or 
0.0714  gm.  Fe  remaining  unoxidized.  Then  0.324  (Fe 
taken)  —  0.0714  (Fe  unoxidized)  =  0.2566  gm.  Fe  oxi- 
dized by  bleaching  powder.  Since  56  parts  Fe  correspond 
to  35.5  parts  CI,  we  have  the  proportion  : 

56 :  35.5  =  0.2566  :  0.1601  gm.  available  CI. 

0.5  gm.  bleaching  powder  contains  0.1601  available  CI 

1     gm.  contains  32.02, 

or  32.02  per  cent  available  CI. 


CHAPTER    XXXVII. 

ACETATE   OF   LIME. 

The  best  method  of  analysis  consists  in  distilling  a 
weighed  quantity  of  the  sample  repeatedly  with  excess 
of  hydrochloric  acid,  and  in  the  distillate  determining  the 
acidity,  and,  since  some  of  the  hydrochloric  acid  distills 
over,  that  must  also  be  determined  and  substracted  from 
the  amount  of  acid  found.     (Fres.,  Zeitschrift,  V.,  315.) 

The  process  is  as  follows  : 

Weigh  out  10  gms.  of  the  sample,  wash  it  into  a  small 
retort  with  30  c.  c.  of  water,  connect  the  retort  with  a  good 
Liebig  condenser,  add  8  c.  c.  hydrochloric  acid,  and  distill 
to  small  bulk.  Then  add  30  c.  c.  of  water,  and  distill 
again.  Repeat  this  operation  at  least  once  more.  Com- 
bine all  the  distillates  and  make  the  volume  up  to  500  c.  c. 
By  this  time,  you  will  have  all  the  acetic  acid  from  the 
sample  as  acid  in  the  distillate.  Take  two  portions  of  100 
c.  c.  each  from  the  distillate.  In  one  portion  (representing 
2  gms.  of  the  sample),  determine  the  acidity  by  titration 
with  normal  potassium  hydrate  solution.  The  result 
would  show  the  amount  of  acetic  acid  obtainable  from  2 
gms.  of  the  sample,  were  it  not  that  some  of  the  hydro- 
chloric acid  used  has  also  distilled  over.  Therefore,  in  the 
other  100  c.  c.  we  must  determine  the  amount  of  hydro- 
chloric acid  present.  For  this  we  use  the  tenth  normal 
argentic  nitrate  solution  (volumetric).  The  solution  must, 
however,  be  first  rendered  neutral.  For  this  purpose  we 
use  pure  calcium  carbonate  in  excess,  which  must  be  care- 
fully tested  for  chlorides,  none  of  which,  of  course,  should 
be  present.  About  5  gms.  of  calcium  carbonate  mil  be 
amply  sufficient.  Stir  it  in  well,  warm  up  the  solution, 
add  a  few  drops  of  potassium  chromate,  and  test  with  the 
tenth  normal  silver  nitrate  solution  as  described  (p.  215). 


222  ACETATE    OF   LIME. 

Since  we  use  a  tenth  normal  solution,  divide  the  number 
of  c.  c.  used  by  10,  and  then  subtract  the  result  from  the 
number  of  c.  c.  of  normal  potassium  hydrate  solution 
used.  The  remainder  gives  the  number  of  c.  c.  of  potas- 
sium hydrate  solution  neutralized  by  the  acetic  acid  from 
2  gms.  of  the  sample.  From  this,  the  amount  of  acetic 
acid  and  percentage  of  pure  acetate  of  lime  present  can  be 
readily  calculated. 
For  example,  suppose 
100  c.  c.  of  distillate  neutralized  19. 9  c.  c.  normal  KHO, 
and  100  c.  c.  "        "  "  5  c.  c.  tenth  n.  Ag]ST03. 

Then,  19.9  —  0.5  =*  19.4  c.  c.  normal  KHO  neutralized  by 

the  acetic  acid  from  2  gms.  of  the  sample, 
19.9  X  0.06  (equivalent,  of  HC2H302  =  60)  =  1.194  gms.  of 
acetic  acid  in  2  gms.  of  the  sample, 
1.194  X    5  =  5.97  gms.  acetic  acid  in    10  gms.  of  sample, 
or  X  50  =  59.7     "        "         "    in  100    "      "       " 

Then  (2HC2H302 :  Ca(C2H302)2  -)  120  :  158  =  59.7 :  x. 
x  =  78. 605  per  cent  Ca(C2H302)2  in  the  sample. 
(For  other  methods,  seeFres.,  Zeitschrift^'XlII^  153,  and 
Am.  Chem.,  VI,  294.) 


CHAPTER    XXXVIII. 

GUANO. 

Phosphoric  Acid. — Fuse  1  gm.  with  5  gms.  sodium  car- 
bonate, and  5  gms.  nitrate  in  a  platinum  crucible  over  a 
Bunsen  burner,  removing  the  flame  as  soon  as  the  fusion 
is  complete,  which  should  be  in  about  half  an  hour. 
Eemove  the  contents  of  the  crucible  with  hot  water, 
acidulate  with  nitric  acid,  and  boil.  The  crucible  can  be 
cleaned  with  dilute  nitric  acid  without  injury.  Filter  out 
any  siliceous  residue  which  may  remain  undissolved,  dilute 
the  solution  up  to  1  litre,  and  determine  phosphoric 
acid  in  one  fifth  (200  c.  c.)  by  means  of  ammonium  molyb- 
date,  as  usual,  using  about  50  c.  c  of  the  molybdate  solu- 
tion. 

Ammonia. — To  determine  the  ammonia  or  nitrogen, 
select  a  tube  of  hard  glass,  15  or  18  inches  long,  draw  one 
end  of  it  to  a  line  point,  and  to  the  other  end  fit  tightly  a 
cork,  through  which  is  passed  a  tube  bent  at  right  angles, 
the  other  end  of  which  passes  through  a  cork  closing 
tightly  one  arm  of  a  bulbed  U-tube.  Into  the  combustion- 
tube  first  slip  a  loosely-fitting  plug  of  asbestos  previously 
ignited,  and  then  some  three  or  four  inches  of  dry  soda 
lime.  Weigh  out  1  gm.  of  the  guano,  pulverize  coarsely 
some  of  the  soda-lime  in  a  mortar,  mix  this  soda-lime  with 
the  guano,  and  introduce  the  mixture  into  the  combustion- 
tube.  Enough  soda-lime  must  be  taken  to  make  the 
charge  fill  the  tube  to  within  three  or  four  inches  of  the 
open  end.  Then  fill  up  with  soda-lime  to  within  about 
an  inch  of  the  end,  place  another  plug  of  ignited  asbestos 
at  the  end,  and  close  with  the  cork  carrying  the  tube. 

Now  run  into  the  bulbed  U-tube  10  c.  c.  of  half -normal 
sulphuric  acid  from  a  burette,  adjust  the  cork  carrying 
the  connection  to  the  combustion-tube,  and  lay  the  com- 


224  guano. 

bus tion- tube  in  the  trough  of  the  combustion-furnace,  sup- 
porting the  bulb-tube  by  a  clamp.  Begin  to  heat  at  the 
forward  end  (nearest  the  cork),  and  get  the  soda-lime, 
which  is  unmixed  with  the  charge,  white  hot  before  the 
heat  is  applied  to  the  charge  mixed  with  the  guano.  Then 
carry  the  heat  slowly  back  until  the  entire  contents  of  the 
tube  are  at  a  white  heat.  Avoid,  however,  heating  the  end 
which  is  drawn  to  a  point,  lest  the  pressure  in  the  tube 
cause  it  to  blow  out.  Keep  up  the  heat  until  no  more 
bubbles  of  gas  are  forced  through  the  acid  in  the  bulb- 
tube.  Then  connect  the  other  limb  of  the  bulb-tube  with 
an  aspirator,  start  the  aspirator  slowly,  and  then  break 
off  the  fine  point  of  the  combustion-tube,  at  the  same  time 
removing  the  heat.  Draw  a  slow  current  of  air  through 
the  tube  until  it  is  well  cooled  down,  and  then  disconnect 
the  bulb-tube  and  pour  the  contents  into  a  beaker,  rinsing 
it  out  well.  Add  a  few  drops  of  cochineal  solution,  and 
by  means  of  normal  KHO  solution  determine  how  much 
of  the  sulphuric-acid  solution  used  has  been  neutralized 
by  the  ammonia  thus  obtained  from  the  guano.  From  the 
data  thus  obtained  the  percentage  of  ammonia  or  nitrogen 
may  be  readily  calculated.  Thus,  suppose  8  c.  c.  of  the 
sulphuric  acid  remained  unneutralized,  2  c.  c,  then,  have 
been  neutralized  by  the  ammonia ;  1  c.  c.  =  0.049  H2S04  = 
0.017  NH3  or  =  0.014 1ST,  and  the  guano  contains  2  X  100  X 
0.017  =  8.4  per  cent  1^H3,  or  2.8  nitrogen  (md.  Fres., 
§186,  §187.) 

Sulphuric  Acid. — Fuse  1  gm.  with  5  gms.  sodium  car- 
bonate and  2  gms.  nitrate,  in  a  platium  crucible  over  a 
Eunsen  burner.  Wash  the  fused  contents  as  completely 
as  possible  from  the  crucible  with  hot  water,  rinse  out  the 
crucible  with  hydrochloric  acid,  add  it  to  the  solution, 
acidulate  with  hydrochloric  acid,  boil,  filter  if  necessary, 
and  determine  sulphuric  acid  with  barium  chloride  as 
usual. 

Water. — Dry  1  to  2  gms.  to  constant  weight,  at  120°  C, 
in  a  weighed  capsule.     The  loss  is  water.     Then  ignite  the 


ORGANIC    MATTER,    ETC.  225 

capsule  at  strong  red  heat  to  constant  weight.  The  loss  is 
organic  and  volatile  matter,  including  ammonia.  Deduct 
the  ammonia  found  elsewhere,  the  difference  is  non-ni- 
trogenous organic  and  volatile  matter.  Of  course,  this  is 
only  approximate.  The  residue  after  .igniting  is  mineral 
matter,  including  phosphoric  acid.  Subtract  the  phos- 
phoric acid  found.  The  difference  is  CaO,MgO,Fe203 
Al303S03Si03.  Report  as  mineral  matter.  S03  may  be 
driven  out  by  the  ignition,  if  there  is  no  more  than  enough 
CaO  and  MgO  to  saturate  the  phosphoric  acid.  A  quali- 
tative test  on  a  hydrochloric  acid  solution  of  the  ignited 
residue  will  show  whether  all  the  S03  has  been  expelled. 

report.    . 

Phosphoric  acid  (P205)* 

Ammonia  (NH3)f , 

Sulphuric  acid  (S03) 

Water  (H2 O) 

Mineral  matter -, 

Non-nitrogenous  organic  and  volatile  matter 

*  Equivalent  to  phosphate  of  lime 

f        "  "nitrogen.,,,.,,  ,,, , 


CHAPTER    XXXIX. 

RAW   SUGAR. 

The  points  usually  determined  in  the  ordinary  commer- 
cial analysis  are  the  amount  of  crystallizable  cane  sugar, 
glucose,  water,  and  ash. 

The  usual  method  of  determining  the  amount  of  crystal- 
lizable cane  sugar  is  by  the  saccharimeter  or  polariscope, 
an  instrument  whose  use  depends  upon  the  different  action 
of  solutions  of  sugar  on  polarized  light,  and  so  constructed 
that  the  per  cent  of  cane  sugar  is  read  off  directly  upon 
the  scale. 

A  certain  amount  of  sugar  to  be  examined  (for  the 
ordinary  Soliel  saccharimeter,  26.048  gms.),  is  dissolved 
in  80  c.  c.  of  cold  water,  2  or  3  c.  c.  of  basic  acetate  of 
lead  added,  the  solution  diluted  to  exactly  100  c.  c,  and 
filtered  through  a  large,  dry,  corrugated  filter.  The  basic 
acetate  (subacetate  or  triplumbic  acetate),  is  prepared  by 
digesting,  at  a  moderate  heat,  7  parts  of  finely  powdered 
litharge,  6  parts  of  neutral  lead  acetate,  and  30  parts  of 
water.  If  the  basic  acetate  does  not  clear  the  solution,  or 
the  solution  filters  badly,  add  a  few  drops  of  solution  of 
sodium  sulphate,  prepared  by  dissolving  1  part  of  the 
salt  in  5  parts  of  water.  If  any  salt  of  lead  pass  through 
the  filter,  making  the  filtrate  turbid,  dip  a  rod  into  acetic 
acid,  and  stir  the  liquid  with  it.  This  will  dissolve  the  lead 
salt  and  clear  the  solution. 

If  the  filtered  liquid  is  too  much  colored  for  the  sac- 
charimeter, filter  it  through  bone  coal  equivalent  in  bulk 
to  8  or  10  c.  c.  The  coal  should  be  previously  ground 
moderately  fine,  and  heated  for  a  few  minutes,  to  a  point 
just  below  redness,  to  expel  moisture.  Care  must  be  taken 
not  to  heat  the  bone-black  enough  to  burn  the  carbon,  and 
turn  it  white,  as  it  will  then  lose  the  power  of  decoloriz- 


POLAKISCOPE    TEST — INVERSION.  22? 

ing  sugar  solutions.  As  the  coal  has  the  power  of  absorb- 
ing sugar  from  the  solution,  thereby  rendering  it  weaker, 
the  filtrate  should  be  poured  back  on  the  filter  several 
times  before  using  it  in  the  saccharimeter. 

The  tube  intended  to  hold  the  sugar  solution  should 
be  first  washed  out  with  the  same,  and  filled  slowly 
to  avoid  the  presence  of  bubbles  of  air.  The  glass  caps 
should  not  be  pressed  on  the  ends  of  the  tube  with  the 
finger,  but  slid  on  gently  and  cautiously,  so  as  to  exclude 
all  air. 

To  adjust  the  saccharimeter,  fill  the  tube  with  pure  dis- 
tilled water,  and  turn  the  instrument,  until  the  semi-disks 
are  of  the  same  color.  It  should  then  read  zero.  Now 
fill  the  tube  with  the  solution  to  be  tested,  having  pre- 
viously washed  it  with  the  same.  The  2  semi-disks  will 
no  longer  have  the  same  color.  Turn  the  instrument  by 
means  of  the  button,  arranged  for  the  purpose,  until  they 
have  the  same  color,  and  read  on  the  scale  the  per  cent  of 
cane  sugar. 

It  is  well  also  to  test  the  instrument  with  a  solution  of 
sugar,  of  known  value.  The  color  to  be  used  depends 
upon  the  preference  of  the  operator.  The  rose  tint  is  best 
adapted  to  most  eyes,  and  has  the  advantage,  that,  with 
the  slightest  change  in  the  instrument,  one  semi-disk 
becomes  instantly  red,  and  the  other  green. 

The  amount  of  cane  sugar  in  a  sample  of  raw  sugar  can 
be  estimated  by  first  determining  the  per  cent  of  invert 
sugar  in  a  portion  by  the  copper  solution,  as  directed  later, 
and  then,  after  converting  a  portion  entirely  into  invert 
sugar,  again  determining  the  per  cent.  The  difference  in 
the  results  is  equivalent  to  the  glucose  produced  by  the 
conversion,  which  is  to  be  calculated  to  cane  sugar.  One 
hundred  parts  of  invert  sugar  correspond  to  95  parts  of  cane 
sugar. 

To  invert  the  cane  sugar,  dissolve  1  gm.  of  the  sugar  in 
100  c.  c.  of  water,  add  1.2  c.  c.  of  concentrated  sulphuric 
acid,  and  heat  on  a  water-bath  for  half  an  hour,  replacing. 


228  RAW    SUGAR 

from  time  to  time,  the  water  lost  in  evaporation.  Neutral- 
ize the  free  acid  with  a  dilute  solution  of  sodium  carbon- 
ate, dilute  to  200  c.  c,  and  proceed  as  directed. 

The  determination  of  glucose  requires  a  solution  of  cop- 
per sulphate,  and  an  alkaline  solution  of  Rochelle  salt 
(sodium  and  potassium  tartrate).  These  solutions,  when 
mixed,  constitute  what  is  called  Fehling's  solution.  It  is 
better,  however,  to  keep  them  separate  (combining  only 
when  required),  as  the  mixture  is  apt  to  decompose,  if  kept 
long. 

To  prepare  the  copper  solution,  dissolve  34.640  gms.  of 
copper  sulphate  in  2u0  or  300  c.  c  of  distilled  water,  cool, 
dilute  to  exactly  500  c.  c,  and  keep  in  a  glass-stoppered 
bottle.  Five  c.  c.  of  this  solution  will  then  correspond  to 
0.05  gm.  grape  sugar.  To  prepare  the  Rochelle  salt  solu- 
tion, dissolve  68  gms.  of  pure  sodium  hydrate  in  about  400 
c.  c.  of  distilled  water,  add  187  gms.  of  Rochelle  salt,  heat 
on  a  water-bath,  with  frequent  stirring,  until  all  is  dis- 
solved, cool,  dilute  to  exactly  500  c.  c.  and  keep  in  a 
glass-stoppered  bottle. 

To  make  the  analysis,  introduce  5  c.  c.  of  the  copper 
sulphate  solution,  5  c.  c.  of  the  Rochelle-salt  solution,  and 
5  c.  c.  of  water,  into  a  10-inch  test-tube  or  tall  narrow 
beaker,  and  also  2  or  3  small  fragments  of  washed  and 
ignited  pumice-stone,  to  prevent  bumping  of  the  fluid  when 
heated,  boil  and  add  (little  at  a  time),  from  a  burette,  the 
sugar  solution  to  be  tested,  which  should  not  contain  more 
than  0.5  per  cent  of  sugar.  If,  upon  trial,  it  is  found  that 
all  the  copper  is  precipitated  by  less  than  10  c.  c.  of  the 
sugar  solution,  dilute  the  solution  with  an  equal  quantity  of 
water  and  repeat  the  test.  If,  on  the  contrary,  it  is  found 
that  more  than  25  c.  c.  are  required,  make  a  solution  of 
the  sugar  of  twice  the  strength,  and  repeat.  The  liquid 
must  be  kept  alkaline.  Toward  the  end  of  the  operation, 
a  slight  cloud  is  formed  upon  adding  the  sugar  solution  ; 
at  the  close,  the  fluid  loses  its  blue  color,  becoming  nearly, 
if  not  quite,    colorless.     If  excess   of  sugar  solution  is 


GLUCOSE — MOISTURE — ASH.  229 

added,  the  fluid  becomes  yellow,  and  brown  if  very  great 
excess  is  added.  Violette  says  that  the  average  of  the 
readings  when  the  cloud  forms,  and  when  the  fluid  becomes 
yellow,  is  the  true  one. 

To  test  the  copper-sulphate  solution,  dry  at  100°  C.  some 
pure  powdered  cane  sugar,  weigh  1  gm.,  dissolve  it  in  100 
c.  c.  of  water,  add  1.2  c.  c.  of  pure  sulphuric  acid,  heat  on 
a  water-bath  for  half  an  hour,  cool,  neutralize  with  sodium 
carbonate,  dilute  to  exactly  200  c.  c,  and  titre  with  it  5  c.  c. 
of  the  copper- sulphate  solution  mixed  with  5  c.  c.  of  the 
Rochelle-sart  solution  and  5  c.  c.  of  water.  If  the  solution 
of  copper  sulphate  is  accurate,  it  should  require  9.5  c.  c. 
of  the  sugar  solution. 

To  determine  moisture,  dry  a  weighed  quantity  of  the 
sugar  to  constant  weight,  at  100°  C.  It  is  well  not  to  take 
more  than  0.5  gm.  of  sugar,  as  the  operation  is  sometimes 
very  tedious,  where  a  large  quantity  is  used,  and  the  dan- 
ger of  decomposing  the  sugar  by  long-continued  heating- 
great.  The  heat  must  not  exceed  105°  C,  as  a  higher  tem- 
perature will  caramel  the  sugar. 

In  determining  the  ash,  different  methods  are  used.  The 
first  consists  simply  in  weighing  out  3  or  4  gms.  in  a  plat- 
inum dish,  and  burning  at  a  low  red  heat  until  the  ash 
appears  white.  This  operation  is  extremely  tedious,  and 
involves  some  loss  of  alkaline  salts  in  consequence  of  the 
prolonged  exposure  to  a  high  temperature  necessary.  A 
method  much  used  in  France  consists  in  adding  a  few  c.  c. 
of  concentrated  sulphuric  acid  to  3  or  4  gms.  of  the  sugar 
in  a  platinum  capsule,  and  incinerating  as  before.  From 
the  weight  of  the  ash  thus  obtained  one  ninth  is  sub- 
tracted, and  the  figure  remaining  is  reported  as  the  ash  of 
the  sugar.  The  most  accurate  method  consists  in  carboniz- 
ing the  sugar  at  a  high  heat  for  a  short  time,  pulverizing 
the  carbon  thus  obtained,  extracting  from  it  the  alkaline 
salts  by  boiling  with  water,  filtering,  evaporating,  and 
gently  igniting  the  filtrate  in  a  platinum  dish,  and  then 
incinerating  the  carbonaceous  matter  insoluble  in  water. 


230  RAW   SUGAR. 

This  gives  the  proportion  of  soluble  and  insoluble  ash, 
their  sum  being,  of  course,  equal  to  total  ash.  The  three 
methods  give  results  sometimes  differing  widely  from  one 
another  when  tried  on  the  same  sample.  In  any  case, 
where  carbonization  of  the  sugar  begins,  the  sugar  is  apt 
to  boil  up,  and  care  must  be  exercised  lest  some  loss  may 
be  experienced  in  consequence. 

To  examine  sugar  or  molasses  for  artificial  glucose  (made 
from  starch)  weigh  out  18.86  gms.  of  the  sample  to  be 
tested,  dissolve  in  water,  invert  by  acidulating  and  heat- 
ing, cool,  neutralize  with  sodium  carbonate,  dilute  to  100 
c.  c,  and  examine  in  the  polariscope  at  a  temperature  of 
92°  C.  The  percentage  of  artificial  glucose  present  will 
then  be  indicated  on  the  scale.  (See  Journ.  Am.  Chern. 
Soc.,  Yol.  I.,  p.  2.) 


CHAPTER  XL. 

SUGAR   (ULTIMATE  ANALYSIS). 

Percentages  of  C,  R,  and  0.—  The  carbon  and  hydrogen 
are  determined  at  one  operation  by  combustion  in  a  stream 
of  dry  oxygen,  the  resulting  C02  and  H20  being  caught 
in  suitable  apparatus  and  weighed  in  those  combinations. 
The  oxygen  is  determined  by  difference.  Select  a  tube  of 
hard  glass  about  28  inches  long,  and  5  or  6  tenths  of  an 
inch  internal  diameter,  fit  to  each  end  corks  through  which 
are  passed  tubes  of  about  1  tenth  inch  internal  diameter, 
and  3  or  4  inches  in  length.  About  2  inches  from  the  front 
end  of  the  tube  (the  end  to  be  attached  to  the  apparatus 
for  absorbing  C02  and  H20),  place  a  plug  of  asbestos,  pre- 
viously ignited  to  remove  all  moisture  and  carbonaceous 
material.  Back  of  this  plug  put  enough  freshly -ignited 
CuO  to  fill  the  tube  a  little  more  than  half,  and  push  down 
upon  this  another  plug  of  ignited  asbestos.  Provide  at 
the  rear  end  of  the  tube  two  bottles,  with  corks  and  tubes, 
for  drying  the  O  and  removing  from  it  any  traces  of  C02  it 
may  contain,  by  bubbling  it  through  the  bottles,  contain- 
ing, respectively,  concentrated  H2S04  and  strong  KHO, 
having  the  sulphuric  acid  next  to  the  tube.  For  the  froni" 
end,  have  a  tube  filled  with  neutral  calcium  chloride  in 
fragments,  through  which  a  current  of  dry  carbon  dioxide 
has  been  passed  for  some  time,  followed  by  a  current  of 
dry  air.  To  absorb  the  carbon  dioxide,  prepare  a  U-tube, 
filled  with  soda-lime,  constructed  in  the  same  manner  as 
given  for  the  determination  of  C02  in  limestone  (p.  63) 
or  carbon  in  iron  (p.  106).  The  sugar,  being  previously 
dried  thoroughly  at  100°  C,  0.250  gm.  is  then  to  be 
weighed  out  in  a  platinum  boat.  Weigh  the  calcium- 
chloride  tube  and  the  soda-lime  tube.  Connect  the  com- 
bustion-tube (laid  in  the  trough  of  the  combustion-fur- 


232  SUGAR  (ultimate  analysis.) 

nace)  at  the  rear  end  with  the  bottles  of  sulphuric  acid  and 
potassium  hydrate,  and  at  the  front  end  directly  with  the 
aspirator,  heat  it  to  redness,  and  then  draw  a  current  of 
air  through  it  until  cool.  Then  introduce  the  platinum 
boat  into  the  rear  end,  replace  the  cork,  and  connect  the 
calcium -chloride  tube  and  soda-lime  tube  at  the  front  end, 
connecting  the  last  with  the  aspirator.  Draw  a  slow 
current  of  air  through  the  tube,  and  begin  to  heat  the 
front  end  of  the  CuO,  carrying  the  heat  slowly  back- 
ward toward  the  boat  containing  the  sugar.  At  the 
same  time,  keep  the .  rear  end  over  the  tube  mod- 
erately, carrying  the  heat  slowly  forward.  Arrange  it 
so  that  the  CuO  shall  be  heated  highly  before  the  sugar 
begins  to  burn.  Just  before  the  heat  reaches  the  boat, 
attach  the  tube  from  the  oxygen  cylinder,  and  force  a  slow 
current  of  the  gas  through  the  tube.  Heat  the  sugar  very 
moderately,  so  that  it  will  burn  slowly  and  not  force  the 
gases  off  too  rapidly.  When  it  is  completely  consumed, 
which  may  be  seen  by  the  disappearance  of  the  black  car- 
bon, remove  the  heat,  disconnect  the  oxygen  cylinder,  and 
draw  a  current  of  air  through  it  until  it  is  cool.  Then 
detach  the  tubes  and  weigh.  The  increase  in  weight  of 
the  calcium-chloride  tube  represents  water,  from  which 
the  percentage  of  hydrogen  may  be  calculated,  the  in- 
crease in  weight  of  the  soda-lime  tube  represents  the  car- 
bon dioxide,  to  be  calculated  to  C. 


CHAPTER  XLI. 

TURPENTINE    (ULTIMATE    ANALYSIS.) 

^10-"  16 

Percentages  of  C  and  H. — The  process  pursued  is  essen- 
tially the  same  as  that  in  the  ultimate  analysis  of  sugar. 
A  few  modifications  only  are  necessary,  since  in  this  case 
we  are  dealing  with  a  volatile  liquid  instead  of  a  solid. 
*  The  pieces  of  apparatus  necessary,  are  the  same  as  for  the 
sugar  analysis,  with  the  exception  of  the  platinum  boat  in 
which  the  sugar  is  weighed.  Instead  of  this  a  small  bulb 
of  thin  glass  is  prepared,  the  ' '  tail' '  of  which  is  drawn  to 
a  long  fine  point.  The  extreme  point  is  then  broken  off,  so 
as  to  leave  an  opening  into  the  interior,  which  should  be 
as  fine  as  a  hair.  The  bulb  is  weighed  and  then  warmed, 
and  the  end  being  immersed  below  the  surface  of  some  tur- 
pentine, the  contraction  of  the  air  in  the  bulb,  as  it  cools, 
will  draw  some  of  the  liquid  into  the  bulb.  Before  it  is 
quite  cold,  withdraw  the  point  from  the  turpentine,  that 
the  contraction  may  draw  the  liquid  out  of  the  "tail," 
leaving  it  clear.  Then  wipe  the  "tail"  dry,  and  seal  the 
end  by  a  moment' s  exposure  to  a  blow-pipe  flame.  The 
glass  should  be  so  thin  that  this  can  be  readily  accom- 
plished. Weigh  again.  The  increase  in  weight  of  the 
bulb  gives  the  weight  of  the  turpentine  taken.  Half -fill 
the  combustion-tube  with  ignited  copper  oxide  as  before, 
drop  in  the  bulb  containing  the  turpentine,  just  crack  it  by 
a  light  blow  from  a  glass  rod,  introduced  for  the  purpose, 
and  immediately  pour  down  upon  it  some  more  copper 
oxide  which  has  been  ignited  and  cooled  out  of  contact 
with  the  air.  Conduct  the  remainder  of  the  operation  as 
in  the  case  of  sugar,  carrying  the  heat  back  more  slowly 
and  carefully.  A  longer  tube  than  that  used  for  sugar 
analysis  may  be  used  with  advantage.  Carry  the  heat 
quite  to  the  end  of  the  copper  oxide  before  stopping  the 
operation. 


CHAPTER  XLII. 

BONE-BLACK. 

Water. — Dry  1  gm.  at  170°  C.  to  constant  weight.  The 
loss  is  water. 

Carbon  Dioxide. — Introduce  into  the  flask  of  a  C02 
apparatus  5  gms.  of  the  finely  pulverized  black,  add  30 
c.  c.  dilute  hydrochloric  acid,  and  determine  the  carbon 
dioxide  by  absorption  in  soda-lime.     Calculate  to  CaC03.* 

After  the  determination  of  the  carbon  dioxide  in  the 
manner  first  given  (by  absorption  with  soda-lime)  pour  the 
contents  of  the  flask  upon  a  filter  and  wash  thoroughly. 
There  will  then  be  a  residue  and  a  solution. 

The  residue  consists  of  sand,  clay,  carbon,  and  insoluble 
organic  matter.  Wash  it  from  the  filter  into  a  weighed 
platinum  dish,  allow  it  to  settle,  decant  off  the  clear  fluid 
as  closely  as  possible  without  disturbing  the  residue,  evapo- 
rate, dry  at  170°  C,  and  weigh.  Weight  ==  sand,  clay, 
and  carbon,  plus  dish.  Ignite  until  all  carbon  is  burned 
off,  and  weigh  again.  Weight  =  sand  and  clay,  plus  dish. 
Difference  from  above  weight  reported  as  carbon.  In  the 
solution  add  barium  chloride,  to  precipitate  the  sulphuric 
acid,  filter  off,  weigh  the  BaS04,  and  calculate  the  sul- 
phuric acid  to  CaS04.  Dilute  the  filtrate  to  500  c.  c,  and 
divide  into  two  parts  ;     A  =  100  c.  c,  B  =  400  c.  c. 

A. — Dilute  to  500  c.  c,  and  take  100  c.  c.  (representing  one 

*  In  most,  if  not  all,  sugar-houses,  the  common  method  of  determining  car- 
bon dioxide  is  a  volumetric  process,  the  volume  of  gas  evolved  being  measured 
by  an  instrument  invented  by  Dr.  C.  A.  Scheibler,  a  full  description  of  which  will 
be  found  in  Fres.,  Quant.  Anal.,  §  237,  or  in  Crookes's  Special  Methods,  p.  390. 
From  the  latter  work,  p.  397,  the  following  table  of  corrections  for  temperature 
of  the  volume  of  gas  obtained  has  been  taken  : 


TABLE  FOR  SCHEIBLER'S   APPARATUS. 


235 


82 


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236  BONE-BLACK. 

fifth  of  a  gm.),  add  about  10  c.  c.  cone,  nitric  acid,  evapo- 
rate nearly  to  dryness  to  expel  hydrochloric  acid,  add  50 
c.  c.  ammonium  molybdate,  and  determine  phosphoric  acid 
as  usual.     Calculate  to  Ca3(P04)2. 

B. — Add  4  or  5  c.  c.  cone,  sulphuric  acid,  evapo- 
rate nearly  to  dryness,  add  25  or  30  c.  c.  water,  and  100 
c.  c.  alcohol.  The  precipitate  is  BaS04-f-CaS04.  Filter 
out,  wash  well  with  water,  from  the  filtrate  boil  out  the 
alcohol,  reduce  the  iron  with  zinc  and  platinum,  as  in  iron 
ore,  and  titre  with  potassium  permanganate.  Calculate 
to  FeO. 

Nitrogen,  chlorine,  and  alkalies  may  sometimes  be  re- 
quired. 

For  chlorine,  boil  5  gms.  with  nitric  acid,  filter,  and 
determine  by  Ag!N"03  in  the  filtrate.  For  nitrogen  and 
alkalies,  see  Guano  and  Superphosphate,  pp.  197  and  222. 

A  mechanical  test  of  the  size  of  the  black  is  frequently 
made.  For  this  purpose  100  gms.  is  weighed  out  and 
shaken  in  a  series  of  ten  wire  sieves,  the  meshes  of  which 
are  of  gradually  decreasing  size,  thus  : 

No.    1  has      6  holes  to  linear  inch. 


cc 

2 

u 

8 

a 

3 

a 

10 

a 

4 

u 

20 

a 

5 

a 

30 

u 

6 

a 

40 

a 

7 

u 

50 

a 

8 

a 

60 

\i 

9 

a 

80 

c< 

10 

a 

100 

•in 

e 

u 

120 

To  get  the  average  fineness  of  the  black,  multiply  the 
weight  left  on  each  sieve  by  the  number  of  meshes  of  that 
sieve  to  the  inch,  add  the  products  together,  and  divide  by 
100. 

To  determine  the  weight  of  a  cubic  foot  of  the  black, 
select  a  small  porcelain  capsule,  weigh,  then  fill  with  the 


ABSORPTIVE   AND   DECOLORIZING   POWER.  237 

black,  level  with,  the  brim  without  shaking  down,  weigh 
again,  and  then  weigh  the  capsule  full  of  water  ;  and  this 
gives  all  the  data  necessary  for  calculating  the  specific 
gravity  of  the  black  when  lying  loosely.  From  this  the 
weight  of  a  cubic  foot  may  be  calculated.  That  of  a  cubi^ 
foot  of  water  is  usually  taken  as  62^  lbs.  (62£  lb»-  Watts1 s 
Diet,  V.,  1010.) 

To  determine  the  absorptive  powe^  ot  the  black — rhe 
porosity — weigh  out  20  gms.  in  a  funnel,  drench  with 
water,  allow  the  surplus  water  to  drain  off,  and  weigh 
again.  The  amount  of  water  retained  shows  the  degree 
of  porosity. 

Decolorizing  Power. — Make  a  solution  of  raw  sugar 
of  10°  Be.  (about  1.07  sp.  gr.),  take  20  to  50  gms.  of  the 
sample,  and  the  same  amount  of  a  bone-black  the  power 
of  which  is  known.  Wet  the  samples  down  well  with  the 
raw-sugar  solution,  and  pass  equal  amounts  of  the  solution 
through  each  sample.  Compare  the  depth  of  color  left  in 
the  sugar  solutions,  after  filtration,  with  one  another  by 
means  of  a  Duboscq  colorimeter. 

Completeness  of  burning  is  determined  by  boiling  a 
portion  of  the  sample  with  solution  of  sodium  or  potassium 
hydrate.  The  deeper  the  coloration  of  the  alkaline  solu- 
tion the  less  complete  the  burning  has  been,  since  organic 
matters  occurring  in  the  coal,  which  have  been  incom- 
pletely carbonized,  impart  a  strong  color  to  solutions  of 
caustic  alkalies. 

Completeness  of  Washing. — Wash  with  hot  water,  and, 
after  cooling,  test  the  density  of  the  wash-water. 


CHAPTER    XLIII. 

COAL. 

Moisture. — Dry  2  gms.  of  the  coal,  finely  pulverized,  in 
a  weighed  platinum  crucible  at  115°  C.3  for  half  an  hour, 
cool,  and  weigh.  Dry  again  for  15  minutes  at  the  same 
temperature,  cool,  and  weigh  again.  Repeat  this  until  the 
weight  begins  to  increase,  indicating  incipient  oxidation. 
From  the  lowest  weight  thus  obtained  calculate  the  per- 
centage of  moisture. 

Volatile  Combustible  Matter. — Ignite  the  above  crucible 
and  contents  for  three  minutes  (keeping  the  crucible 
closely  covered)  in  the  strongest  heat  of  a  good  Bunsen 
burner,  then  at  once  ignite  for  the  same  length  of  time 
over  the  blast-lamp,  cool,  and  weigh.  The  crucible  should 
be  kept  covered  throughout  this  operation.  The  loss  is 
volatile  combustible  with  half  the  sulphur.  For  anthracite 
or  coals  containing  no  bituminous  matter,  this  operation 
may  be  omitted  as  unnecessary. 

Fixed  Carbon. — Remove  the  cover,  and  burn  off  the 
remaining  carbon  over  a  Bunsen  burner  until  nothing 
remains  but  the  ash.  The  loss  is  fixed  carbon  with  the 
remainder  of  the  sulphur.  The  final  weight,  less  the  weight 
of  the  crucible,  gives  the  ash. 

Sulphur. — Pulverize  the  coal  finely,  weigh  out  2  gms. 
and  mix  it  thoroughly  in  a  convex  cover  with  16  gms. 
sodium  carbonate  and  16  gms.  sodium  nitrate,  also  finely 
pulverized.  Now,  with  a  spatula  introduce  a  little  of  the 
mixture  into  a  large  platinum  crucible,  cover  it,  and  heat 
until  deflagration  commences,  when  the  flame  should  be 
removed.  As  soon  as  the  violence  of  the  deflagration  has 
ceased,  add  a  little  more  of  the  mixture,  and  apply  the 
flame  again  until  deflagration  again  occurs.  Repeat  this 
until  all  of  the  mixture  has  been  transferred  to  the  cru- 
cible.    Heat  after  the  last  violent  deflagration  has  ceased,, 


KEEPING   NOTES — SPECIFIC    GRAVITY.  239 

until  the  mass  is  in  complete  fusion  to  insure  oxidation  of 
the  sulphur.  Dissolve  out  the  contents  of  the  crucible  in 
boiling  water,  acidulate  with  HC1,  boil  to  remove  the  lower 
oxides  of  nitrogen,  if  anything  remains  undissolved,  filter 
and  wash.  In  the  solution,  precipitate  the  sulphur  (now 
present  as  sulphate)  with  BaCl2  in  the  manner  already 
given  (p.  18.) 

The  most  convenient  method  of  keeping  the  notes  on  a 
coal  analysis  are  as  follows,  an  example  being  given  to 
show  how  the  calculation  is  made  : 

Weight  of  crucible  and  coal 32.0000    gms. 

"crucible 30.0000 

Goal  taken 2.0000 

Weight  of  crucible  +  coal 32.0000 

.    "   .  "  "   after  drying 31.9920 

Loss  =  HaO 0.0080  0.40  per  cent. 

Weight  of  crucible  +  coal  dried 31.9920 

"    ignited  (closed) 31.4480 

Loss  =  volatile  combustible  +  %&.:..    0.5440  27.20        " 

Weight  of  crucible  +  coal  ignited  (closed). . . .  31.4480 
"    ignited  (open)  30.1000 

Loss  =  fixed  carbon  +  %  S 1.3480  67.40       " 

Weight  of  crucible  +  contents  ignited  (open).  30.1000 
-      "  " 30.0000 

Residue  =  ash 0.1000  5.00 

Sulphur 1 

REPORT. 

Moisture 0.40  per  cent. 

Volatile  combustible  (27.20  less  0.5  or  ^  S) 26.70 

Fixed  carbon  (67.40  less  0.5  or  %  S) 66.90 

Ash 5.00 

Sulphur 1.00 

100.00 

Weight  of  a  Given  Volume  of  the  Coal  (1  cubic  yard). — 
By  weighing  a  fragment  of  the  coal  suspended  from  the 
balance  by  a  hair  in  air  and  then  in  water  the  specific 
gravity  may  be  obtained.     The  weight  of  a  cubic  yard  may 


240  COAL. 

/hen  be  calculated,  e.  g.:  Suppose  the  specific  gravity  to  be 
1.3488. 

Now,  1  cubic  foot  of  water  weighs  62. 355  lbs.  (  Watts'  s 
Diet.,  Y.,  p.  1010),  and  1  cubic  yard  weighs  62.355  X  27 
=  1683.585  lbs.  .  • .  1  cubic  yard  coal  weighs  1683.585  X 
1.3488  =  2270.819  lbs.  or,  leaving  off  the  decimals  2271 
lbs.  The  weight  of  1  cubic  foot  of  water  may  be  regarded 
as  62i  lbs. 

Ultimate  or  Elementary  Analysis  of  Coal. — This  is 
conducted  in  the  same  manner  as  for  sugar,  which  see 
p.  230. 

Heating  Power. — Berthier's  method,  by  the  reduction 
of  lead  oxide  (Handb.  der  Met.  Analyt.  Chem.,  I.,  207; 
Kerl.,  Hutten-Tcunde,  I.,  218),  is  thus  described: 

Mix  1  gm.  of  the  finely  pulverized  coal  carefully 
with  not  less  than  20  or  more  than  40  times  its  weight  of 
finely  sifted  litharge  containing  no  metallic  particles, 
place  the  mixture  in  a  small  crucible,  and  cover  it  with  30 
times  its  weight  of  litharge.  That  the  mixture  may  not 
boil  over,  the  crucible  should  be  only  about  half  full.  Cover 
the  crucible,  and  heat  gradually  in  a  muffle  or  wind  fur- 
nace to  red  heat.  If  the  heat  is  raised  too  rapidly,  com- 
bustible gases  escape,  or  the  mass  may  boil  over.  In 
using  a  wind  furnace,  the  crucible  should  be  placed  on  a 
fire-brick,  resting  on  the  grate  bars  supporting  the  glow- 
ing coals.  Shake  coals  around  it  until  only  the  top  of  the 
crucible  projects.  When  the  mass,  which  at  first  swells 
up,  is  fused,  cover  the  crucible  entirely  with  coals,  and 
increase  the  heat  for  ten  minutes  to  collect  the  lead  in  a 
button,  and  then  take  it  out.  The  whole  operation  lasts 
from  forty-five  minutes  to  one  hour.  Break  up  the  cru- 
cible, clean  the  button  from  adhering  lead  oxide  by  means 
of  a  brush,  and  weigh.  To  obtain  a  reliable  average  make 
two  to  four  tests.  Forchammer  (Bgwfd.,  XL,  30)  recom- 
mends, instead  of  litharge,  a  mixture  of  3  parts  litharge 
with  1  part  lead  chloride,  which  fuses  more  readily  and 
requires  only  ten  minutes  for  the  operation.     As  unity  we 


HEATING    POWER.  241 

refer  to  carbon,  which  reduces  34  times  its  weight  of  lead. 
Sugar  carbon  gives  nearly  this  quantity  of  charcoal ;  with  1 
to  1.5  per  cent  ash,  only  29  to  30  parts.  If  we  assume  1 
caloric  as  8086  (Favre  and  Silbermann)  every  part  of  lead 

QfxOfi 

produced  —  -~r  =  230  heat  units.      Since  this  is   based 

upon  Welters'  s*  law,  it  gives  no  absolutely  correct  results, 
but  they  do  not  differ  appreciably  from  the  truth,  so  that 
this  process  on  account  of  its  simplicity  is  still  of  value, 
and  it  is  still  frequently  used.  (Winkler  Erdm.  Jr.  fvc 
PraM.  Chem.,  XVII.,  65;  V.  Hauer*  Oesterr.  Zeitschr. 
€LIIL,  34,  156,  249.)  The  results  are  at  most  one  ninth  toe 
low,  as  estimated  against  the  calculation  from  elementary 
analysis,  and  according  to  Stolzel  (Dingl.  Polyt  J 
€XLVL,  138)  are  the  closer  the  higher  the  percentage  of 
carbon,  and  the  greater  the  care  exercised  to  avoid  loss  of 
carbon  monoxide. 

*  Welters's  law  may  be  briefly  stated  thus  :  The  absolute  heating  effects  of  car- 
bon and  hydrogen  stand  in  direct  relation  to  the  amounts  of  oxygen  taken  up  in 
burning.  Thus,  one  part  by  weight  of  H  stoichiometrically  calculated  requires 
thrice  as  much  O  as  one  part  of  C,  e.  g. : 

2  parts  hydrogen  take  16  parts  O  to  form  H20  or  1  pt.  H  takes  8  pts.  O. 
12    "      carbon        "      32      "      "        "      CO,    "   1  pt.  C     "    2%  "   O. 
.  \  Heating  effect  of  H  :  Heating  effect  of  C  '=  3  : 1. 

Experimental  researches  show  the  absolute  heating  effect  of  H  as  compared 
with  C  to  be  4.2  : 1  (Favre  and  Silbermann  ib.). 


CHAPTER   XLIV. 

PETROLEUM. 

Petroleum  consists  of  a  mixture  of  hydrocarbons,  prin- 
cipally of  the  so-called  paraffine  series,  CnH2n+2,  in  which 
the  temperatures  of  boiling  or  melting  increase  as  the 
number  of  atoms  of  carbon  in  the  molecule  increase. 
Thus,  the  first  four  of  the  series  are  gaseous  at  ordinary 
temperatures,  the  next  two  or  three  boil  at  a  temperature 
below  that  of  boiling  water,  the  rest  at  a  still  higher  tem- 
perature. As  the  number  of  carbon  atoms  in  the  molecule 
increase,  the  boiling  point  becomes  higher  and  higher. 
'?hose  members  of  the  series  containing  twenty  atoms  of 
carbon  or  more  in  the  molecule  are  solid  at  ordinary  tem- 
peratures (commercial  paraffines),  etc.  (vid.  Fowne's  Ele- 
mentary CTiem.). 

The  chief  value  of  a  petroleum  lies  in  the  amount  and 
quality  of  burning,  and  heavy  paraffine  oil  which  can  be 
obtained  from  it.  This  is  determined  by  subjecting  the 
oil  to  what  is  called  ''fractional  distillation,"  keeping  the 
portions  distilling  off  at  different  temperatures  apart  from 
each  other,  and  then  determining  the  amount  and  quality 
of  the  fractions.  What  distills  off  first  is  known  as  the 
naphtha,  and  is  inferior  in  value.  The  last  portions,  after 
distilling  off  the  heavy  paraffine  oils,  have  also  little  or 
no  value.     The  process  is  thus  conducted : 

The  gravity  of  the  oil  at  60°  F.  is  first  taken.  Then  500 
or  1000  c.  c.  of  the  oil,  preferably  the  larger  quantity,  is 
weighed,  and  placed  in  a  retort  connected  with  a  good 
Liebig  condenser.  A  cork,  carrying  a  thermometer  which 
will  register  temperatures  at  least  as  high  as  500°  F.,  is 
then  fitted  to  the  tubulure  of  the  retort  and  heat  is  applied. 
The  oil  is  gradually  raised  to  the  temperature  of  boiling. 
Being  a  mixture  of  hydrocarbons  having  different  boiling 
points,   the  temperature   does  not  remain  constant,  but 


DISTILLATION.  243 

steadily  increases.  As  soon  as  the  thermometer  indicates 
150°  F.,  the  receiver  is  changed,  and  another  is  substituted. 
This  is  again  changed  at  250°  F.  These  first  two  fractions 
are  the  light  and  heavy  naphtha.  The  fraction  between 
250°  and  400°  is  the  light-,  and  that  between  400°  and  500° 
the  heavy -burning  oil.  If  it  is  only  desired  to  determine 
the  quantity  and  quality  of  the  illuminating  oils  which 
the  petroleum  will  yield,  we  may  stop  here.  If  it  is  de- 
sirable to  go  on,  the  heat  is  removed  for  a  moment  while 
the  thermometer  is  taken  out  and  replaced  by  a  close-fit- 
ting ground-glass  stopper.  The  heat  is  then  replaced,  and 
the  distillation  continued  until  but  a  small  amount  is  left 
in  the  retort.  In  some  cases,  two  or  three  fractions  are 
made  of  the  last  portion  coming  off  after  500°.  Having  the 
fractions,  the  next  step  is  to  determine  their  amount  and 
quality.  Measure  and  weigh  each  one,  and  take  the 
specific  gravity  as  a  check  on  the  results.  It  must  be 
remembered  that  loss  is  involved  in  every  transfer  of  the 
oil  from  one  vessel  to  another  ;  therefore  the  best  plan  is  to 
weigh  the  receivers  for  the  fractions  beforehand.  The 
specific  gravity  is  usually  reported  in  degrees  Baume. 
Since,  however,  there  are  several  tables  giving  the  com- 
parison of  Baume  degrees  and  specific  gravities  which 
differ  from  one  another  more  or  less  widely,  it  is  well  also 
to  record  the  specific  gravity,  which  may  be  ascertained 
most  readily  and  accurately  by  weighing  a  small  piece  of 
glass  or  brass  suspended  from  a  hair  in  the  oil,  then  in  air* 
and  in  water. 

REPORT. 

Gravity  of  the  oil °Baume  (  =  sp.  gr ) 

The  oil  was  found  to  contain  : 

Temperature. , Per  Cent > , — Gravity — > 

Fahr.       By  Vol.    By  Wt.    Be.  =Sp.Gr. 

J?*ht'     I  Naphtha  70°tol50°     

Heavy,  y  JNapntna 150°  to  250°     

Light.     )    n„min„     .,  250°  to  400°     

Heavy,  f   BurmnS  ol1 400°  to  500°     

Parafnne  oils 500°  upward 

Residue  (cokings) 


244  PETROLEUM. 

Refined  burning  oils  sometimes  require  to  be  tested  for 
"flashing"  and  "burning"  points  ;  or,  in  other  words,  it 
may  become  necessary  to  determine  at  what  temperature 
the  oil  will  evolve  an  inflammable  vapor,  and  at  what  tem- 
perature it  will  take  fire  when  brought  near  a  flame.  The 
test  is  made  by  placing  a  small  portion  of  the  oil  in  a  glass 
vessel  surrounded  by  water,  immersing  a  thermometer  in 
the  oil,  and  slowly  heating  the  water,  which,  in  turn,  im- 
parts heat  to  the  oil.  The  oil  should  be  frequently  stirred 
to  insure  uniform  heating,  and  from  time  to  time  a  small 
flame  is  brought  near  the  surface  of  the  oil.  The  tempera- 
ture should  not  be  raised  faster  than  3°  in  five  minutes. 
When  the  "flashing  point"  is  reached,  on  the  approach 
of  a  flame,  a  light  blue  flame  runs  over  the  surface  of  the 
oil,  accompanied  with  a  slight  explosive  sound.  The  indi- 
cation of  the  thermometer  is  then  noted.  The  heat  is  still 
raised  until  the  application  of  the  flame  will  set  the  oil  on 
fire,  and  it  will  remain  burning  when  the  flame  is  removed. 
The  indication  of  the  thermometer  is  then  noted  as  the 
"burning  point."  The  operation  should  be  conducted  in 
So  place  not  exposed  to  draughts.  The  flame  should  not 
be  frequently  applied  to  the  surface  of  the  oil,  lest  the 
upper  layer  of  the  oil  should  be  heated  up  to  the  flashing 
point,  while  the  lower  layers,  the  temperature  of  which  is 
shown  by  the  thermometer,  are  still  below  that  tempera- 
ture. A  good  quality  of  burning  oil  should  not  flash  below 
110°  P. 


CHAPTER    XLV. 

EXAMINATION    OF   ILLUMINATING    GAS. 

The  tests  most  frequently  made  or  required  in  deter- 
mining the  value  of  illuminating  gas  are  :  Specific  grav- 
ity, illuminating  power,  sulphur  and  ammonia. 

The  Specific  Gravity  may  be  determined  by  Bunsen's 
method  of  weighing  a  glass  globe  when  exhausted  by  an 
air-pump,  when  filled  with  air,  and  when  filled  with 
the  gas,  and  from  the  data  obtained  calculating  the  re- 
sult. The  more  convenient  and  more  common  method 
at  present  in  gas-testing  stations  is  the  Schilling  effusion 
test,  in  which  the  times  of  effusion  of  equal  volumes  of 
gas  and  air  through  a  fine  hole  in  a  thin,  metallic  plate 
are  compared.  The  principle  upon  which  it  depends 
being  that  the  specific  gravities  of  two  gasses  passing 
through  such  an  opening  are  proportionate  to  the  squares 
of  the  times  of  effusion.  As  the  specific  gravity  of  ail 
is  taken  as  1.000,  if  a  given  volume  of  air  escapes  in  139 
seconds,  and  the  same  volume  of  gas  requires  but  90  sec- 
onds, the  calculation  would  be  : 

Sp.  gr.  of  air  (=  1)  :  Sp.  gr.  of  gas  =  (139*  =)  19,321 
:   (902  =)  8,100 
Sp.  gr.  of  gas  =  £«»  =  0.419 

Illuminating  Power. — The  methods  most  relied  upon 
in  taking  the  illuminating  power  depend  upon  the  princi- 
ple that  the  intensity  of  light  varies  inversely  as  the 
square  of  the  distance  from  its  source.  If,  then,  between 
two  lights  which  are  to  be  compared  we  place  a  light 
screen  and  move  it  back  and  forth  until  both  sides  are 
equally  illuminated,  its  respective  distances  from  the  two 
lights  will  be  as  1  to  1  if  they  are  equal  in  intensity  ;  as  1 
to  4  if  one  is  twice  as  bright  as  the  other  ;  as  1  to  9  if  one 
is  thrice  as  bright,  and  so  on. 


246  EXAMINATION   OF   ILLUMINATING   GAg. 

If  one  of  these  lights  is  assumed  as  a  standard,  we 
have  then  a  measure  of  the  illuminating  power  of  the 
other  in  terms  of  the  standard. 

The  Standard  adopted  is  the  light  derived  from  a  sperm 
candle,  of  which  six  weigh  one  pound,  and  each  of  which 
will  burn  120  grains  per  hour.  These  candles  are  manu- 
factured at  present  expressly  for  this  purpose.  When 
cast  in  the  moulds  they  are  made  slightly  tapering  from 
the  butt  in  order  to  facilitate  their  removal  when  cooled. 
This  taper  should  be  removed  by  drawing  them  through 
a  plate  like  a  wire-drawing  plate,  that  they  may  be  uni- 
form in  calibre.  This  process  is  sometimes  neglected  by  the 
manufacturer,  so  that  each  candle  should  be  examined 
before  using  to  see  that  it  is  of  uniform  diameter  through- 
out. If  the  candle — as  is  frequently  the  case — does  not 
burn  exactly  120  grains  per  hour,  a  correction  may  be 
made  for  the  variation,  provided  it  does  not  exceed  6  grains 
on  either  side  of  this  rate,?',  e.,  is  between  114  and  126 
grains.  If  those  limits  are  exceeded  the  results  should  be 
rejected. 

The  Burner  for  the  gas  was  originally  required  by 
British  acts  of  Parliament  to  be  "  an  argand  burner  hav- 
ing 15  holes  and  a  7-inch  chimney.  "  This  description 
was,  however,  not  found  to  be  sufficiently  close,  as  a  large 
variety  of  burners  might  answer  this  description,  and 
give  very  different  results  with  the  same  gas. 

A  pattern,  however,  answering  this  description  was  man- 
ufactured, and  for  a  long  time  both  here  and  in  England 
known  as  the  ' l  Standard  London  argand. ' '  More  recently, 
however,  the  question  of  standards  for  gas  has  been 
overhauled  in  England,  and  standard  burners  manufac- 
tured by  Sugg,  of  London,  have  been  adopted,  of  which 
the  material  dimensions  of  the  various  parts,  &c. ,  are  accu- 
rately specified.  It  is  sufficient  here  to  state  that  for  gas 
of  under  20  candle  power  the  burner  known  as  "Sugg's 
London  argand  'No.  1 "  is  used.  This  is  provided  with  a 
steatite  (commonly   called  lava)  chamber  with  24  holes, 


PHOTOMETRY — METER.  247 

aud  a  chimney  of  6  inches  in  height,  and  an  internal 
diameter  of  1|  inches.  For  gas  of  nnder  16  candle-power 
a  chimney  of  If  inches  internal  diameter,  and  of  the  same 
height,  is  nsed  with  the  same  burner.  For  cannel  gas  and 
other  rich  gases,  a  steatite  bats  wing  burner  is  used.  In 
this  country  for  gas  running  up  to  30  candle  power 
another  burner  manufactured  by  Sugg,  and  similar  to  his 
' '  London  argand  No.  1,  '  is  used,  which  is  provided  with  32 
holes  and  a  9-inch  chimey. 

Meters. — The  rate  at  which  the  gas  is  to  be  burned  is  5  ft. 
per  hour.  As  the  duration  of  a  test  is  ordinarily  not  over 
i5  minutes,  an  experimental  meter  registering  to  thou- 
sandths of  a  foot  is  necessary.  A  wet  meter  is  used  in 
which  the  water  is  brought  to  a  given  level  indicated  by 
a  mark  on  the  gauge.  In  some  photometric  rooms  a 
clock  striking  every  minute  with  a  preliminary  alarm  5 
seconds  before  it  strikes  is  used ;  but  the  most  recently 
constructed  meters  for  this  purpose  are  provided  with  a 
hand  run  by  clock  work,  which  will  travel  around  the 
face  of  the  meter  with  the  meter  hand,  if  the  gas  burns  at 
exactly  the  rate  of  5  ft.  per  hour,  while  if  it  does  not,  the 
amount  by  which  the  one  hand  is  in  advance  of  the  other 
furnishes  a  basis  for  a  simple  calculation  of  the  rate  per 
hour  for  which  a  correction  must  be  made,  in  calculating 
the  candle  power. 

Photometer  Bar  and  Disc. — The  photometer  bar  is  sim- 
ply the  bar  on  which  the  disc  is  moved  back  and  forth 
between  the  two  lights,  and  is  graduated  so  that  by  the 
aid  of  a  pointer  immediately  below  the  disc  the  candle 
power  observed  may  be  at  once  read  off.  The  lights  are 
usually  placed  at  100  inches  apart.  The  disc  formerly 
used  was  of  paper  stretched  in  a  small  circular  frame, 
oiled  except  a  small  spot  in  the  centre.  The  form  at  pres- 
ent used  is  a  paper  with  a  star-shaped  hole  in  the  centre 
between  two  thin  plain  papers,  the  whole  set  in  a  frame, 
and  inclosed  in  a  box  blackened  inside  to  exclude  reflec- 


248  EXAMINATION    OF   ILLUMINATING-   GAS. 

tions,  and  prevent  the  glare  of  the  lights  which  are  com- 
pared from  distracting  the  attention. 

Pressure,  etc. — The  pressure  at  the  meter  should  be 
equal  to  half  an  inch  of  water,  and  at  the  burner  should  be 
as  nearly  zero  as  possible.  Attention  is  not  always  given  to 
the  barometric  pressure,  and  the  temperature  of  the  room 
in  which  the  tests  are  made.  The  barometer  should  stand 
at  30  inches,  and  the  temperature  should  be  60°  F.  If 
any  great  variation  from  these  figures  occurs,  corrections 
should  be  made  to  obtain  the  true  measurement  of  the  gas 
passed  through  the  meter. 

The  Photometer  Room  should  have  the  walls,  ceiling 
and  floors,  colored  dead  black  to  avoid  reflections,  which 
would  interfere  with  the  correctness  of  the  observations. 

In  making  the  test  the  candle  should  be  first  lighted 
and  allowed  to  burn  for  five  or  ten  minutes  ;  the  gas  also 
should  be  allowed  to  burn  for  about  the  same  length  of 
time,  and  the  rate  of  burning  adjusted  with  a  tangent  screw- 
cock.  The  candle  (or  candles,  since  two  are  now  often 
used)  are  counterbalanced  by  the  use  of  shot  or  sand,  and 
at  the  same  instant  the  time  is  noted.  With  the  most  im- 
proved forms  of  apparatus,  the  candles  are  balanced  and 
weighed  in  position.  With  some  other  forms,  the  balance 
is  separate  from  the  rest  of  the  apparatus,  and  provided 
with  a  socket  at  one  end  of  the  beam  to  receive  the  candle. 
The  disc  is  then  moved  back  and  forth  on  the  bar  until 
both  sides  appear  to  be  equally  illuminated,  and  the  read- 
ing is  taken  once  and  sometimes  twice  a  minute.  The 
meter  is  also  observed  every  minute  to  insure  uniformity 
of  burning  of  the  gas.  These  readings  are  of  course 
recorded  as  fast  as  made,  and  after  ten  or  fifteen  minutes 
an  average  is  taken  ;  the  amount  of  candle  burned  is  ascer- 
tained by  adding  grain  weights  to  the  pan  under  the  can- 
dle socket  to  replace  the  weight  burned,  and  the  time 
noted.  In  this  way  the  candle  and  gas  rates  are  obtained  ; 
the  photometer  readings  are  averaged,  and  where  two  can- 
dles have  been  used,  the  figure  obtained  is  doubled.     This 


CANDLE    POWEE — SULPHUR.  249 

gives  observed  candle  power,  which  must  be  corrected  for 
both  gas  and  candle  rates. 

Correction  for  Gas  and  Candle. — If  the  gas  has  burned 
at  the  rate  of  over  5  feet  per  hour,  the  observed  candle  power 
is  too  high ;  if  the  gas  rate  is  less  than  5  feet  it  is  too  low. 
We  therefore  correct  by  a  proportion  : 

Gas  rate  :  5  ft.  =  obs.  c.  p. :  c.  p.  corrected  for  gas. 

This  result  must  again  be  corrected  for  candle  rate  by  a 
similar  proportion.  If  the  candle  rate  is  over  120  grains, 
the  reading  has  been  too  low  ;  if  under  120  grains,  it  is  too 
high.  The  proportion  therefore  is  :  120  :  candle  rate  =* 
c.  p.  :  corrected  candle  power.  These  corrections  may  be 
made  in  either  order,  when,  if  the  arithmetic  is  correct, 
the  result  will  be  essentially  the  same.  E.  g.\  Suppose 
the  observed  candle  power  to  be  17.12,  the  gas  rate  4.9, 
the  candle  rate  124  grains  : 

In  correcting  first  for  e;as  rate, 

4.9  :  5  =  17.12  :  candle  power  corrected  =  17.46. 

Correcting  this  for  candle  rate, 

120  :  124  =  17.46  :  correct  candle  power  =  18.04. 

Or,  to  correct  first  for  candle  rate, 

120  :  124  ==  17.12  :  candle  power  corrected  ==  17.69. 

Then,  for  gas  rate, 

4.9  :  5  =  17.69  :  correct   candle  power  =  18.05. 

Essentially  the  same  result. 

Sulphur. — This  is  determined  in  gas  by  burning  the 
gas  slowly  in  such  a  way  that  the  products  of  combustion 
mingle  with  fumes  of  ammonia  or  its  carbonate,  collect- 
ing the  ammonia  compounds  of  the  sulphur  thus  obtained 
(sulphate  and  sulphite),  oxidizing  them  to  sulphate,  and 
determining  as  usual  by  precipitation  with  barium  chloride. 
An  experiment  meter  registering  to  thousandths  of  a 
foot  is  used,  and  from  four  to  ten  feet  of  gas  are  burned 
for  a  determination,  at  the  rate  of  from  half  a  foot  to 
one  foot  per  hour.  Two  forms  of  apparatus  are  used, 
"Letheby's"  and  "the  Referee's."  In  the  first  (which 
is  the  older  form)  the  gas  is  burned  in  a  Leslie  burner, 


250  EXAMINATION    OF   ILLUMINATING   GAS. 

which  consists  of  a  number  of  small  metal  tubes, 
arranged  in  a  ring  like  an  argand  burner.  Below  the 
burner  is  placed  a  beaker  containing  ammonia,  over  which 
a  funnel  is  inverted,  the  stem  of  the  funnel  coming  up 
through  the  centre  of  the  burner.  Over  the  burner  is  a 
trumpet  tube,  in  shape  like  a  long  truncated  cone,  the 
upper  end  of  which  is  turned  at  right  angles  and  passes 
through  a  cork  in  a  horizontal,  cylindrical  " receiver," 
shaped  like  a  double-ended  bottle,  with  a  shoulder  at 
each  end.  In  the  receiver  is  also  placed  about  20  c.  c.  of 
strong  ammonia.  To  the  other  end  of  the  receiver  is  fitted 
a  long  tube,  about  the  size  of  combustion  tubing.  This 
tube  is  not  set  quite  horizontal,  but  inclined  slightly  up- 
ward so  that  any  liquids  condensing  in  it  will  flow  back 
to  the  receiver.  It  is  often  also  surrounded  by  a  Liebig 
condenser,  to  insure  more  complete  condensation. 

In  the  Ref  eree'  s  apparatus  the  gas  is  burned  in  a  single 
hole  steatite  jet,  around  which  are  placed  lumps  of  am- 
monium sesquicarbonate,  while  over  it  is  placed  a  trumpet 
tube,  as  in  the  Letheby  apparatus.  Instead  of  the  "  re- 
ceiver," however,  a  tall,  glass  bubbling- jar  is  used,  filled 
with  marbles,  over  which  a  stream  of  ammonia  is  made  to 
trickle  slowly.  The  ammonia  flows  through  a  tube  at 
the  bottom  into  a  beaker  placed  to  receive  it.  To  insure 
sufficient  draught  through  the  marbles  it  is  sometimes 
well  to  attach  an  aspirator  to  the  upper  end  of  the  bub- 
bling-jar,  and  keep  up  an  exhaustion  of  about  one  quar- 
ter to  one  half  an  inch  of  water. 

With  either  apparatus,  after  a  sufficient  amount  of  gas 
has  been  burned ;  the  entire  apparatus,  trumpet  tube  and 
all,  are  thoroughly  washed  out ;  the  washings  and  con- 
tents of  the  receiver,  etc.,  added  together;  the  whole 
evaporated  nearly  or  quite  to  dryness,  a  few  c.  c.  of  bromine 
water  added  and  again  evaporated,  and  finally  water 
added  to  bring  the  solution  up  to  a  convenient  bulk,  and 
the  sulphate  precipitated  as  usual  with  barium  chloride. 

The  sulphur  calculated  from  the  weight  of  barium  sul- 


AMMONIA.  251 

phate  thus  obtained  is  reckoned  to  so  and  so  many  grains 
per  hundred  feet  of  gas,  and  is  so  reported.  The  amount 
depends  on  the  character  of  the  materials  used  in  making 
the  gas,  and  the  kind  and  efficiency  of  the  methods  of 
purification  used.  The  amount  depending  upon  these 
conditions  may  be  from  five  to  over  forty  grains  per  100 
feet. 

Ammonia  is  usually  determined  by  passing  several  feet 
of  the  gas  (measured  by  an  experiment  meter)  slowly 
through  a  measured  quantity  of  half  normal  sulphuric 
acid,  and  then  by  titration  determining  the  amount  of  sul- 
phuric acid  which  has  been  neutralized.  A  Peligot  bulb 
tube,  or  a  tube  filled  with  marbles  wetted  with  the  sulphuric 
acid  solution,  may  be  used  for  the  purpose — indeed,  any 
method  which  permits  the  intimate  contact  of  the  gas 
with  solution,  and  subsequent  removal  of  the  solution 
for  titration.  The  ammonia  (ETHS)  is  calculated  like  the 
sulphur  to  grains  per  100  ft.  The  amount  found  is  usu- 
ally in  the  neighborhood  of  two  to  three  grains,  though 
in  certain  cases  it  may  run  much  higher. 


CHAPTER  XLVI. 

SOAP. 

A  good  hard  soap  should  not  contain  less  than  54  per 
cent  of  fat  acids,  combined  with  at  least  one  eighth  that 
amonnt  of  soda  (Na20),  and  not  over  40  per  cent  of  water. 

In  the  analysis  of  soap,  we  may  have  to  determine 
(1)  combined  fatty  acids,  (2)  unsaponified  fat,  (3)  resin, 
(4)  glycerine,  (5)  combined  alkali  (NaaO),  (6)  uncombined 
alkali  (NaHO),  (7)  free  carbonate  (JSra2C03),  (8)  chloride, 
trace,  (9)  sulphate  (Na2S04),  (10)  foreign  matter,  which 
may  include  impurities  or  adulterants,  as  clay,  sand, 
ochre,  talc,  sodium  silicate,  etc.,  and  (11)  water. 

Analysis. 

Dissolve  5  gms  of  the  soap  in  fine  shavings  in  80  or  90 
c.  c.  of  90  per  cent  alcohol,  heating  it  on  the  water-bath 
until  solution  is  effected. 

The  solution  will  then  contain  the  first  six  constituents 
above-mentioned,  together  with  the  water,  while  the  resi- 
due will  contain  the  other  constituents. 

Solution. — Pass  a  current  of  carbon  dioxide  through  it 
for  some  time.  The  uncombined  alkali  will  be  converted 
into  NaHC03,  and  will  precipitate.  Filter,  wash  with  alco- 
hol, dissolve  in  water,  and  titre  with  half -normal  sulphu- 
ric acid.  (Alkalimetry  p.  207. )  Calculate  to  NaHO  for 
(6)  uncombined  alkali. 

To  the  filtrate  or  the  alcoholic  solution  in  which  C02  failed 
to  produce  a  precipitate,  add  15  or  20  c.  c.  of  water,  and 
evaporate  off  the  alcohol.  Add  25  or  30  c.  c.  of  half- 
normal  sulphuric  acid  from  a  burette,  and  a  weighed 
quantity  (5  gms.)  of  pure  white  wax,  boil,  filter  through 
a  wetted  filter,  and  wash  with  boiling  water  until  the 
washings  are  no  longer  acid.  Cool  the  cake  of  wax  which 
takes  up  the  fat   acids   and  resin,  dry  between  bibulous 


TJNCOMBINED    FAT — RESIN.  263 

paper,  and  weigh.  The  weight,  less  the  weight  of  the 
wax  added,  gives  that  of  (1)  combined  fatty  acids,  (2)  un- 
combined  fat,  and  (3)  resin. 

In  the  filtrate  from  the  wax,  etc.,  determine  by  means 
of  a  half -normal  soda  solution,  how  much  of  the  sulphuric 
acid  used  has  been  neutralized  by  the  alkali  of  the  soap, 
the  result  gives  (5)  combined  alkali.     Calculate  to  Na20. 

Residue. — Dry  and  weigh,  treat  with  water,  and  filter, 
dry  again  and  weigh.  The  last  weight  is  that  of  the  (10) 
foreign  matter  insoluble  in  water.  Titre  the  water  solu- 
tion with  half -normal  sulphuric  acid.  Calculate  the  re- 
sult to  Na2C03.  This  gives  (7)  free  carbonate.  The  first 
weight,  less  the  foreign  matter  insoluble  in  water,  and  also 
less  free  carbonate,  gives  the  weight  of  neutral  salts  sol- 
uble in  water. 

(2)  UneomMned  Fat. — Treat  5  gms.  of  the  soap  (cut 
into  very  fine  shavings)  with  ether  two  or  three  times, 
pouring  off  the  ether  into  a  weighed  dish  The  operation 
may  be  assisted  by  placing  the  vessel  over  a  water-bath 
containing  hot  water,  but  with  no  flame  under  it.  Since 
the  ether  may  dissolve  small  portions  of  the  soap,  it 
is  safer  to  evaporate  off  the  ether  from  the  first  extrac- 
tion, and  then  to  treat  the  residue  again  with  ether. 
The  weight  of  the  residue  left  on  the  last  evaporation  of 
the  ether  gives  (2)  unsaponified  fat.  Carbon  disulphide 
may  be  used  in  place  of  ether. 

(3)  Resin. — Dissolve  40  gms.  of  the  soap  in  boiling 
water,  add  an  excess  of  sulphuric  acid  to  separate  the 
fatty  acids  and  resin,  cool,  pour  off  the  aqueous  portion, 
and  digest  the  fatty  residue  with  equal  volumes  of  alcohol 
and  water,  agitating  from  time  to  time.  Pour  off  the 
milky  fluid,  add  more  alcohol  and  water,  and  digest  again. 
Repeat  this  until  the  fluid  ceases  to  become  milky,  then 
add  water  and  a  weighed  quantity  of  wax  as  before, 
filter,  dry,  and  weigh  the  cake.  The  weight  represents 
that  of  the  fatty  acids  deprived  of  the  resin.  The  differ- 
ence of  percentage  obtained  in  this  way  from  the  percent- 


254  soap. 

age  obtained  as  before  described,  gives  approximately  the 
amount  of  the  resin  present. 

(4)  Glycerine. — Dissolve  5  gms.  of  the  soap  in  90  per 
cent  alcohol,  add  dilute  alcoholic  sulphuric  acid  (1  vol. 
concentrated  sulphuric  acid  to  10  vols,  alcohol)  so  long 
as  a  precipitate  forms,  filter,  wash  with  alcohol,  digest 
with  barium  carbonate  and  water  until  the  alcohol  is  gone, 
filter,  evaporate  the  filtrate  to  dryness  in  a  weighed  dish 
at  gentle  heat,  and  weigh  the  residue  of  glycerine. 

(5,  6,  7,  8,  9,  and  10)  Mineral  Constituents. — Calcine  5 
gms.,  weigh,  dissolve  in  water,  filter.  Residue  is  (10) 
foreign  matter.  Dilute  the  solution  to  some  convenient  bulk 
(say  200  c.  c).  In  one  half,  determine  total  alkali  (5,  6,  and 
7)  by  titration  with  half -normal  sulphuric  acid.  A  portion 
may  be  taken  to  test  for  the  presence  of  potassium  salts. 
In  one  quarter,  determine  (8)  chloride,  by  titration  with 
standard  solution  of  silver  nitrate,  with  potassium  chro- 
mate  as  indicator.  In  the  remaining  quarter,  determine 
(9)  sulphate,  by  precipitation  with  barium  chloride,  as 
usual.      Calculate  chloride  and  sulphate    to    ISTaCl  and 

(11)  Water. — Some  analysts  determine  all  the  other 
constituents,  and  calculate  the  remainder  as  water.  It 
may,  however,  be  determined  by  dissolving  1  or  2  gms.  in  as 
little  strong  alcohol  as  possible,  pouring  the  solution  upon 
a  weighed  quantity  of  sand  in  a  dish,  and  drying  in  the 
air-bath  at  110°  C.  to  constant  weight.  The  loss  represents 
the  water. 


CHAPTER    XLVII. 

FLOUR. 

Digest  5  gms.  of  the  flour  in  100  c.  c.  cold  water  for 
one  or  two  hours,  with  frequent  stirring,  filter  through  a 
filter  previously  exhausted  with  hydrochloric  acid,  washed, 
dried,  and  weighed,  wash  with  about  100  c.  c.  cold  water. 
The  solution  contains  (1)  albumen,  (2)  gum,  (3)  sugar,  and 
a  portion  of  the  soluble  salts.  The  residue  contains  (4) 
cellulose,  (5)  starch,  gluten,  and  fat. 

Solution. — 1.  Boil,  and  then  filter  ;  the  precipitate  con- 
sists of  albumen.     Dry  at  100°  C,  and  weigh. 

[Note. — The  treatment  with  water,  filtration  and  pre- 
cipitation of  albumen  should  be  completed  on  the  same 
day.  By  keeping  the  solution  hot  it  may  be  continued 
through  two  days,  but  this  is  not  advisable.] 

2.  Evaporate  the  filtrate  from  the  albumen  nearly  to 
dryness,  add  a  large  excess  of  alcohol,  warm,  and  then 
allow  it  to  cool,  filter  on  a  weighed  filter,  wash  with  alco- 
hol.    Dry  at  100°  C,  and  weigh  the  gum  thus  obtained. 

3.  Evaporate  the  alcoholic  filtrate  from  the  gum  to  small 
bulk,  add  water,  and  boil  out  the  alcohol.  Concentrate 
the  solution  to  50  c.  c,  and  divide  in  halves.  In 
the  first  half,  determine  the  glucose  direct  by  the 
copper  sulphate  solution  as  described  under  Raw  Sugar 
(p.  225).  In  the  second  half,  add  a  few  drops  of  dilute 
sulphuric  acid,  boil,  neutralize  with  potassium  hydrate, 
and  determine  glucose  by  copper  sulphate  as  before.  The 
excess  of  glucose  found  in  the  second  determination  is  due 
to  cane  sugar. 

Residue. — Wash  with  a  jet  from  the  wash-bottle  into  a 
beaker.  Then  dry  the  filter  with  what  adheres  to  it,  and 
weigh.  This  weight,  less  that  of  the  filter  found  at  the 
beginning,  gives  the  weight  of  adhering  substance,  which 


256  FLOUR. 

must  be  taken  into  account  in  the  subsequent  determina- 
tions. 

4.  Add  to  the  substance  in  the  beaker,  50  times  its 
weight  of  water  containing  one  per  cent  of  sulphuric  acid, 
and  heat  for  several  hours,  until  the  starch  goes  into  solu- 
tion, and  only  light  floculent  cellulose  is  left.  Filter  and 
wash  until  all  sulphuric  acid  is  removed,  dry  at  100°  C, 
and  weigh. 

5.  To  the  filtrate  from  the  cellulose,  diluted  to  400  c.  c, 
add  about  30  c.  c.  concentrated  sulphuric  acid,  and  heat 
on  a  water-bath  at  about  95°  C.  for  several  hours,  adding 
water  from  time  to  time  to  keep  it  up  to  the  original  bulk. 
Digest  thus  until  a  drop  of  the  solution  shows  no  colora- 
tion when  treated  with  diluted  iodine  solution,  and  also 
gives  no  precipitate  with  alcohol.  When  the  conversion 
of  the  starch  into  glucose  is  complete,  neutralize  the  excess 
of  acid  by  sodium  or  potassium  hydrate  and  determine  the 
glucose  with  copper  sulphate  as  before. 

The  starch  can  also  be  determined  in  a  separate  portion, 
by  washing  a  weighed  quantity  with  water,  then  with 
ether,  and  again  with  water,  drying  and  then  making  an 
elementary  analysis  for  carbon  (see  elementary  analysis  of 
sugar),  or  with  copper  oxide  and  lead  chromate.  The 
carbon  found  is  from  both  starch  and  cellulose.  Deduct 
the  carbon  due  to  cellulose  found  as  above  (formula, 
C12H10O10  the  same  as  that  of  starch),  and  calculate  the  rest 
to  stai(h  (44  parts  carbon  =  100  parts  starch). 

Albumenoids. — Determine  the  total  nitrogen  in  1  gm. 
by  combustion  with  soda-lime  (guano,  p.  222),  and  from 
this  calculate  the  albumenoids  ;  15.5  parts  N '  =  100  parts 
albumenoids.  From  this  deduct  the  albumen  found  as 
above  ;  the  difference  is  gluten. 

Fat. — Weigh  out  2  or  3  gms.  of  the  flour,  treat  with 
ether,  boiling  it  gently  over  the  water-bath,  decant  the 
ether  through  a  filter  into  a  weighed  dish,  repeat  this  two 
or  three  times,  evaporate  off  the  ether,  and  weigh  the  fat. 

Ash. — Burn  40  or  50  gms.  of  the  flour  in  a  weighed  dish. 


ASH — WATER.  25? 

If  therb  is  any  difficulty  in  burning  off  the  carbon,  cool 
and  weigh  the  dish  and  contents  ;  then  extract  with  hot 
water,  filter  through  a  small  filter,  avoiding  any  transfer  of 
the  carbonaceous  substance  to  the  filter.  Dry  the  dish, 
and  weigh  again.  The  loss  represents  mineral  salts  dis- 
solved out.  Moisten  with  nitric  acid,  add  the  filter-paper 
and  contents,  and  burn  again,  cool,  and  weigh.  The 
weight,  less  that  of  the  dish,  represents  the  remain- 
der of  the  ash.  The  weight  of  the  ash  of  the  small  filter- 
paper  may  be  ignored.  The  ash  may  be  dissolved  in 
water  with  a  little  nitric  acid,  and  analyzed  as  required. 

Water.—  Dry  1  or  2  gms.  in  the  air-bath  at  110  to  120° 
C.  to  constant  weight.     Loss  =  water. 

All  filter-papers  used  in  this  analysis,  on  which  different 
constituents  (albumen,  gum,  etc.)  are  weighed,  should  be 
prepared  by  soaking  for  about  half  an  hour  in  dilute 
hydrochloric  acid  (1 :  10)  washing  thoroughly  with  water, 
and  drying. 


TABLES. 


TABLES    OF    WEIGHTS    A1STD    MEASURES. 


The  following  comparison  of  French,  weights  and  meas- 
ures with  those  of  the  United  States  have  been  taken  or 
calculated  from  similar  tables  given  by  Br.  Warren  De  la 
Rue.     Ure's  Dictionary,  III.,  p.  1119. 

Slight  discrepancies  from  other  authorities  exist,  e.  g., 
the  gramme  is  given  by  De  la  Rue  as  equivalent  to  15.4323 
grains.  The  U.  S.  Dispensatory,  13th  Ed.,  pp.  1734  and 
1735,  gives  15.434  grains,  and  refers  to  other  authorities 
which  give  15.444  grains  as  the  equivalent  of  the  gramme. 

The  number  of  grains  in  the  U.  S.  gallon  of  231  cubic 
inches  is  here  taken  as  58,318,  which  is  believed  to  be  cor- 
rect, from  a  calculation  based  upon  results  obtained  from 
experimental  researches  on  the  expansion  of  liquids,  and  a 
reference  to  the  English  standard  for  the  wine  or  Win- 
chester gallon,  on  which  it  is  based.  (See  note  of  W.  H. 
Chandler,  Am.  Chem.  I.,  318.)  The  U.  S.  Dispensatory 
(ib.)  gives  58,328.886  grains. 

The  report  of  F.  R.  Hassler,  of  the  coast  survey,  gives 
58,372.1754  in  1832,  and  in  1842  Hassler  makes  it  58,373 
grains.  The  reasons  for  considering  this  erroneous  will  be 
found  in  Barnard's  Metric  System,  jx  158. 


262  TABLES. 


MEASURES   OF  CAPACITY 

(U.   S.   PHARMACOPEIA). 

Grains  <rf 

Cubic 

Gal.     Qts.       Pts.        Fl.  oz. 

Fl.  dr.           Minims. 

water  at  62°  F. 

centimetres. 

1    =    4    =    8    =    128    = 

:    1,024    =    61,440 

=    58,318.00    = 

=     3,785.200 

1          2            32 

256           15,380 

14,579.50 

946.300 

1            16 

128            7,690 

7,289.75 

473.150 

1 

8              480 

455.61 

29.570 

1                60 

56.95 

3.690 

1 

0.95 

0.061 

1  English  Imperial  gallon 

=  277.274  cu.  in. 

70,000.00 

4,543.000 

1        "              "         pint 

=    34.659      " 

8,750.00 

568.000 

Other  English  gallons : 

1  wine  c=  Winchester  gal. 

=  231.000      " 

58,318.00 

3,785.200 

1  corn  gallon, 

268.800      " 

67,861.00 

4,402.900 

lale 

282.000      «? 

71,193.40 

4,619.200 

leu.  ft.  =  283.15c.  c. 

1  cu.  in.  =    16.38  c.  c. 

0.061027  cu.  in.  =  1  c.  c. 

LINEAR  MEASURES. 

Metre. 

Metre. 

i  yard 

1  foot ........ 

. .  0.91438 
..  0.30480 

1  inch. .. 

0.0254 

39.3708  inch  ah 

....     1.0000 

TROY  WEIGHT. 

Lb.    Oz.      Dwt.        Grs. 

Grammes. 

1  =  12  =  240  =  5,760 

..  373.2419 

1         20          480. .... 

...     31.1035 

1           24 

1.5552 

1 

. .       0.0648 

AVOIRDUPOIS  WEIGHT. 

ton.  Cwt.    Qr.        St.  Lbs,  Kilogrammes. 

1  =  20  =  80  =  160  =  2,240 1,016.00 

14  8  112 . 50.80 

1  2  28 12.70 

1  14 6.35 

Oz.       Dr.     Grs.  Troy.  Grammes. 

1  =  16  =  256  =  7,000.00 453.5926 

1        16  437.50 28.3495 

1  27.34 1.7718 

1  net  ton  =  2,000  lbs 907  kilogrammes. 

apothecaries'  weight. 

Lb.    Oz.      Dr.  Scruples.  Grains.  Grammes. 

1  =  12  =  96  =  288  =  5,760.. 373.2419 

11        8        24         480 31.1035 

31  3  60 3.8879 

31  20 1.2960 

0.0022  lb.  Av.  =  0.03527  oz.  Av.  =  15.4323  grs 1  gm. 

Lbs.  Av.  Grammes. 

1  cu.  ft.  water  at  62°  F.  =  62.3550 28,315.0000 

lcu.in.      *<        "        "         0.0361 16.38C 

— Watts's  Dictionary,  V.,  1010. 


TABLE  OF  ATOMIC  WEIGHTS. 


Revised  by  C.  F,  CHANDLER  and  F,  G,  WIECHMANN,! 


OCTOBER,   1881. 


Aluminium, 

Al. 

IV. 

27  0 

1     Manganese, 

Mn. 

VI. 

55  0 

Antimony, 

Sb. 

V. 

120-0 

!     Mercury, 

Hg. 

II. 

200  0 

Arsenic, 

As. 

V. 

74  "9 

Molybdenum, 

Mo. 

VI. 

96  0 

Barium, 

Ba. 

II. 

136  8 

Mckel, 

m. 

VI. 

59  0 

Bismuth, 

Bi. 

V. 

2100 

Nitrogen, 

N. 

V. 

14  0 

Boron, 

B. 

III. 

110 

Osmium, 

Os.  11 

.  IV. 

199  0 

Bromine, 

Br. 

I. 

79-7 

Oxygen, 

O. 

II. 

16-0 

Cadmium, 

Cd. 

II. 

1120 

Palladium, 

Pd. 

IV. 

106  0 

Caesium, 

Cs. 

I. 

133  0 

j     Phosphorus, 

P. 

V. 

31  0 

Calcium, 

Ca. 

II. 

40  0 

Platinum, 

Pt. 

IV. 

197  0 

Carbon, 

C. 

IV. 

12  0 

|     Potassium, 

K. 

I. 

39  0 

Cerium, 

Ce. 

III. 

1412 

J    Rhodium, 

Ro. 

IV. 

104  0 

Chlorine, 

CI. 

I. 

35  4 

i     Rubidium, 

Kb. 

I. 

85  0 

Chromium, 

Cr. 

VI. 

52  4 

Ruthenium, 

Ru.  II.  IV. 

104  0 

Cobalt, 

Co. 

VI. 

59  0 

Selenium, 

Se. 

II. 

79  0 

Columbiwm, 

Cb. 

V. 

94  0 

Silicon, 

Si. 

IV. 

280 

Copper, 

Cu. 

II. 

631 

Silver, 

Ag. 

I. 

108  0 

Davyum, 

Da. 

154  0 

Sodium, 

Na. 

I. 

23  0 

Didymium, 

D. 

III. 

147  0 

Strontium, 

Sr. 

II. 

87  5 

Erbium, 

E. 

III. 

169  0 

Sulphur, 

S. 

II. 

32  0 

Fluorine, 

F. 

I. 

19-0 

Tantalum, 

Ta. 

V. 

182-0 

Gallium, 

Ga. 

III. 

69  9 

Tellurium, 

Te. 

II. 

128  0 

Grlucinum, 

Gl. 

II. 

9  2 

Thallium, 

27. 

I. 

204  0 

Gold, 

Au. 

III. 

196  2 

Thorium, 

Th. 

IV. 

231-5 

Hydrogen, 

H. 

I. 

10 

Tin, 

Sn. 

TV. 

1180 

Indium, 

In. 

III. 

113  4 

Titanium, 

Ti. 

IV. 

50  0 

Iodine, 

I. 

I. 

126  5 

Tungsten, 

W.  IV.  VI. 

184  0 

Iridium, 

Ir. 

II. 

198-0 

Uranium, 

U. 

VI. 

240  0 

Iron, 

Fe. 

VI. 

56  0 

Vanadium, 

V. 

V. 

51 -S 

Lanthanum, 

La. 

[III. 

139  0 

Yttrium, 

Y. 

III. 

600 

Lead, 
Lithium, 

Pb. 

n. 

207  0 

Zinc, 

Zn. 

II. 

65  0 

Li. 

i. 

7  0 

Zirconium, 

Zr. 

IV. 

900 

Magnesium, 

Mg. 

ii.  1 

24  0 

1 

Note. — The    Artiads    are    printed    in    Roman,    the   Perissads  in 
Italics. 


264 


TABLES. 


TABLE  OF  SPECIFIC  GRAVITIES  CORRESPONDING  WITH  DEGREES  BEAU  ME  FOR 
LIQUIDS  LIGHTEtt  THAN  WATER. 

The  following  is  taken  from  the  United  States  Dispensatory  (Wood  and 
Bache).  In  that  volume  three  different  values  are  given  for  the  value  of 
degrees  Beaume  in  specific  gravities.  Those  which  follow  were  from  the 
French  Codex : 


Deg. 

Specific 

Deg. 

Specific 

Deg. 

j      Specific 

Deg. 

Specific 

B. 

gravity. 

B. 

gravity. 

B. 

gravity. 

B. 

gravity. 

10..  . 

1.000 

27... 

0.894 

44... 

0.809 

61... 

0.738 

11..  . 

0.993 

28... 

0.889 

45... 

0.804 

62... 

0.735 

12..  . 

0.986 

29... 

0.883 

46... 

0.800 

63... 

0.731 

13..  . 

0.979 

30... 

0.878 

47... 

0.795 

64... 

0.727 

14..  . 

0.973 

31... 

0.872 

48... 

0.791 

65... 

0.724 

15..  . 

0.966 

32... 

0.867 

49... 

0.787 

66... 

0.720 

16.    . 

0.960 

33... 

0.862 

50... 

0.783 

67... 

0.716 

17..  . 

0.953 

34... 

0.857 

51... 

0.778 

68. . . 

0.713 

18..  . 

0.947 

35... 

0.852 

52... 

0.774 

69... 

0.709 

19..  . 

0.941 

36... 

0.847 

53... 

0.770 

70... 

0.706 

20..  . 

0.935 

37... 

0.842 

54... 

0.766 

71... 

0.702 

21..  . 

0.^29 

38... 

0.837 

55... 

0.762 

72. . . 

0.699 

22..  . 

0.923 

39... 

0.832 

56... 

0.758 

73. . . 

0.696 

23..  . 

0.917 

40... 

0.827 

57... 

0.754 

!  74. . . 

0.692 

24..  . 

0.911 

41... 

0.823 

58... 

0.750 

75... 

0.689 

25..  . 

0.905 

42... 

0.818 

59... 

0.746 

I  76... 

0.686 

26..  . 

0.900 

43... 

0.813 

60... 

0.742 

'77... 

0.682 

The  specific  gravity  may  be  calculated  from  the  formula : 

144 


Sp.  gr.  = 


B 


134. 


For  specific  gravities  corresponding  with  degrees  B.  for  liquids  heavier 
than  water,  see  Table  of  values  of  Sulphurie  acid. 


TABLES. 


266 


TABLE  OF  VALUES  OF  SULPHURIC  ACID. 

A.  H.  Elliott,  Proc.  Am.  Chem.  Soc,  II.,  p.  26,  adopted  by  Manufac- 
turing Chemists'  Assoc.  See  Dingier,  CCLX.,  268.  Tables  taken  from 
Kolbe  &  Rosensdtiehl's  results.  Bulletin  de  la  Soc.  Ind.  de  Mulhousey  July 
and  August,  1872,  pp.  209  and  238. 


Degrees  Beaume. 

Specific 
gravity. 

Per  cent 
H2S04. 

Degrees  Beaume. 

Specific 
gravity. 

Per  c'nt 
HaS04. 

1...              

1.005 
1.011 
1.023 
1.029 
1.036 
1.043 
1.050 
1.057 
1.064 
1.071 
1.086 
1.093 
1.100 
1.107 
1.114 
1.122 
1.136 
1.143 
1.150 
1.158 
1.172 
1.179 
1.186 
1.201 
1.208 
1.216 
1.231 
1.238 
1.254 
1.262 
1.269 
1.285 
1.293 

0.93 

1.87 

3.74 

4.67 

5.61 

6.54 

7.48 

8.41 

9.35 

10.28 

12.15 

13.09 

14.02 

14.96 

15.89 

16.83 

18.70 

19.63 

20.57 

21.50 

23.37 

24.31 

25.24 

27.11 

28.05 

29.98 

30.85 

31.79 

33.66 

34.59 

35.53 

37.40 

38.33 

34 

1.309 
1.317 
1.334 
1.342 
1.359 
1.368 
1.386 
1.395 
1.413 
1.422 
1.441 
1.451 
1.470 
1.480 
1.500 
1.510 
1.531 
1.541 
1.562 
1.573 
1.594 
1.616 
1.627 
1.650 
1.661 
1.683 
1.705 
1.727 
1.747 
1.767 
1.793 
1.814 
1.835 

40.20 

2 

35 

36 

41.14 

3 

43.01 

4 

37 

43.94 

5 

38 

45.81 

6          

39 

46.75 

7 

40 

48.62 

8 

41.. 

49.55 

9 

42. 

51.42 

10 

43 

44 

52.36 

11 

54.23 

12 

45 

55.16 

13 

46 

57.03 

14 

47 

57.97 

15 

48 

49 

59.84 

16 

60.77 

17 

50 

51 

62.64 

18 

63.58 

19 

52 

65.45 

20 

53 

66.38 

21 

54 

68.25 

22 

55 

70.12 

23 

56 

71.06 

24 

57 

72.93 

25 

58. 

73.86 

26 

59.. 

75.7a 

27 

60 

77.60 

28 

61.. 

79.47 

29 

62 

81.34 

30 

63 

83.21 

31 

64 

86.02 

32 

65 

88.82 

33 

66 

93.50 

266 


TABLES- 


TABLE  OF  SPECIFIC  GRAVITY  OF  SOLUTIONS  OF  HYDROCHLORIC  ACID.      TEMP., 

15°  (URE). 


Specific 

Per  cent 

Specific 

Per  cent 

Specific 

Per  cent 

gravity. 

HC1. 

gravity. 

HC1. 

gravity. 

HC1. 

1.2000 

40.777 

1.1328 

26.913 

1.0637 

13.048 

1.1982 

40.369 

1.1308 

26.505 

1.0617 

12.641 

1.1964 

39.961 

1.1287 

26.098 

1.0597 

12.233 

1.1946 

39.554 

1.1267 

25.690 

1.0577 

11.825 

1.1928 

39.146 

1.1247 

25.282 

1.0557 

11.418 

1.1910 

38.738 

1.1226 

24.874 

1.0537 

11.010 

1.1893 

38.330 

1.1206 

24.466 

1.0517 

10.602 

1.1875 

37.923 

1.1185 

24.058 

1.0497 

10.194 

1.1857 

37.516 

1.1164 

23.650 

1.0477 

9.786 

1.1846 

37.108 

1.1143 

23.242 

1.0457 

9.379 

1.1822 

36.700 

1.1123 

22.834 

1.0437 

8.971 

1.1802 

36.292 

1.1102 

22.426 

1.0417 

8.563 

1.1782 

35.884 

1.1082 

22.019 

1.0397 

8.155 

1.1762 

35.476 

1.1061 

21.611 

1.0377 

7.747 

1.1741 

35.068 

1.1041 

21 .  203 

1.0357 

7.340 

1.1721 

34.660 

1.1020 

20.796 

1.0337 

6.932 

1.1701 

34.252 

1.1000 

20.388 

1.0318 

6.524 

1.1681 

33.845 

1.0980 

19.980 

1.0298 

6.116 

1.1661 

33.437 

1.0960 

19.572 

1.0279 

5.709 

1.1641 

33.029 

1.0939 

19.165 

1.0259 

5.301 

1.1620 

32.621 

1.0919 

18.757 

1.0239 

4.893 

1.1599 

32.213 

1.0899 

18.349 

1.0220 

4.486 

1.1578 

31.805 

1.0879 

17.941 

1.0200 

4.078 

1.1557 

31.398 

1.0857 

17.534 

1.0180 

3.670 

1.1537 

30.990 

1.0838 

17.126 

1.0160 

3.262 

1.1515 

30.582 

1.0818 

16.718 

1.0140 

2.854 

1.1494 

30.174 

1.0798 

16.310 

1.0120 

2.447 

1.1472 

29.767 

1.0778 

15.902 

1.0100 

2.039 

1.1452 

29.359 

1.0758 

15.494 

1.0080 

1.631 

1.1431 

28.951 

1.0738 

15.087 

1.0060 

1.124 

1.1410 

28.544 

1.0718 

14.679 

1.0040 

0.816 

1.1389 

28.136 

1.0697 

14.271 

1.0020 

0.408 

1.1369 

27.728 

1.0677 

13.863 

1.1349 

27.321 

1.0657 

13.456 

TABJ.KS. 


267 


TABLE  SHOWING  THE  AMOUNT  OF  NITRIC  ACID  (HNOs)  CONTAINED  IN  SOLU- 
TIONS OF  DIFFERENT  SPECIFIC  GRAVITIES.      TEMP.,   15°  (URE). 


HN03 

|     Specific 

HNO3 

Specific 

hno3 

Specific 

per  cent. 

|     gravity. 

per  cent. 

gravity . 

per  cent. 

gravity. 

100 

i     1.5000 

:    66 

1.3783 

33 

1.1895 

99 

1.4980 

65 

1.3732 

32 

1.1833 

98 

1.4960 

64 

1.3681 

31 

1.1770 

97 

1.4940 

63 

1.3630 

30 

1.1709 

93 

1.4910 

62 

1.3579 

29 

1.1648 

95 

1.4880 

61.. 

1.3529 

28 

1.1587 

94 

1.4850 

60 

1.3477 

27 

1.1526 

93 

1.4820 

59 

1.3427 

26 

1.1465 

92 

1.4790 

58 

1.3376 

25 

1.1403 

91 

1.4760 
1.4730 
1.4700 

57 

56 

1  55 

1.3323 
1 . 3270 
1.3216 

24 

23 

22 

1.1345 

90 

1.1286 

89 

1 . 1227 

88 

1.4670 

54 

1.3163 

21 

1.1168 

87 

1.4640 

53 

1.3110 

20 

1.1109 

86 

1.4600 

52 

1.3056 

19 

1 . 1051 

85 

1.4570 

51 

1.3001 

18 

1.0993 

84 

1.4530 

50 

1.2947 

17 

1.0935 

83 

1.4500 

49 

1.2887 

16 

1.0878 

82 

1.4460 

48 

1.2826 

15 

1.0821 

81 

1.4424 

47 

1.2765 

14 

1.0764 

80 

1.4385 

46 

1.2705 

13 

1.0708 

79 

1.4346 
1.4306 

45 

1.2644 
1.2583 

12 

11 

1.0651 

78 

44 

1.0595 

77 

1.4269 

43 

1.2523 

10 

1.0540 

76 

1.4228 

42 

1.2462 

9 

1.0485 

75 

1.4189 

41 

1.2402 

8.  . 

1.0430 

74 

1.4147 

40 

1.2341 

t 

1.0375 

73 

1.4107 

39 

1.2277 

6 

1.0320 

72 

1.4065 

38 

1.2212 

5 

1.0267 

71 

1.4023 

37 

1.2148 

4 

1.0212 

70 

1.3978 

36 

1.2084 

3 ! 

1.0159 

69 

1.3945 

35 

1.2019 

2... 

1.0106 

68 

1.3882 
1.3833 

34 

1.1958 

1 | 

1.0053 

67 

268 


TABLES. 


TABLE  OF    SPECIFIC  GRAVITY  OF    SOLUTIONS  OF    CRYSTALLIZED     TARTARIC 
ACID  IN  WATER.      TEMP.,    15°.      WATER  AT   15°  =  1. 


Gerlach,  " 

Specifische  Gewichte  deb  Salzlosungen." 

Per  cent. 

Specific 

Per  cent. 

Specific 

Per  cent. 

Specific 

gravity. 

gravity. 

gravicy. 

1 

1.00450 

20 

1.09693 

39 

1.20190 

2 

1.00900 

21 

1.10200 

40 

1.20785 

3 

1.01360 

22 

1.10720 

41 

1.21380 

4 

1.01790 

23 

1.11240 

42 

1.21980 

5 

1.02240 

24 

1.11750 

43 

1.22590 

6 

1.02730 

25 

1.12270 

44 

1.23170 

7 

1.03220 

26 

1.12820 

45 

1.23770 

8 

1.03710 

27 

1.13380 

46 

1.24410 

9 

1.04200 

28 

1.13930 

47 

1.25040 

10 

1.04692 

29 

1.14490 

48. 

1.25680 

11 

1.05170 

30 

1.15047 

49 

1.26320 

12 

1.05650 

31 

1.15600 

50 

1.26962 

13 

1.06130 

32 

1.16150 

51 

1.27620 

14 

1.06620 

33 

1.16700 

52 

1.28280 

15 

1.07090 

34 

1.17260 

53 

1.28940 

16 

1.07610 

35 

1.17810 

54 

1.29610 

17 

1.08130 

36 

1.18400 

55 

1.30270 

18 

1.08650 

37 

1.19000 

56 

1.30930 

19 

1.09170 

38 

1.19590 

57 

1.31590 

1ABLE  OF  SPECIFIC  GRAVITY   OF  SOLUTIONS  OF  CRYSTALLIZED   CITRIC  ACID 
IN  WATER.      TEMP.,   15°.      WATER  AT  15°  =  1. 

Gerlach,  "Specifische  Gewichte  der  Salzlosungen." 


Specific 

Specific 

Specific 

Per  cent. 

gravity. 

Per  cent. 

gravity. 

Per  cent. 

gravity. 

1    

1.00370 

23 

1.09300 

45 

1.19470 

2 

1.00740 

24 

1.09720 

46 

1.19980 

3 

1.01110 

25 

1.10140 

47 

1.205C0 

4 

1.01490 

26 

1.10600 

48 

1.21030 

5 

1.01860 

27 

1.11060 

49 

1.21530 

6 

1.02270 

28 

1.11520 

50 

1.22041 

7 

1.02680 

29 

1.11980 

51 

1.22570 

8 

1.03090 

30 

1.12439 

52 

1. 23"70 

9.... 

1.03500 

31  

1.12880 

53 

1.23590 

10........ 

1.03916 

32 

1.13330 

54 

1.24100 

11 

1.04310 

33 

1.13780 

55 

1.24620 

12 

1.04700 

34 

1.14220 

56 

1.25140 

13 

1.05090 

35 

1.14670 

57 

1.25720 

14 

1.05490 

36 

1.15150 

58 

1.26270 

15 

1.05880 

37 

1.15640 

59 

1.26830 

16 

1.06320 

38 

1.16120 

60 

1.27382 

17 

1.06750 

39 

1.16610 

61 

1.27940 

18 

1.07180 

40 

1.17093 

j  62.. 

1.28490 

19 

1.07620 

41 

1.17560 

63 

1.29040 

20 

1.08052 

42 

1.18140 

64 

1.29600 

21 

1.08480 

43 

1.18510 

65 

1.30150 

22 

1.08890     1 

44 

1.18990 

66 

1.30710 

TABLES. 


269 


TABLE  OF  SPECIFIC  GRAVITY   OF   SOLUTIONS   OF   ACETIC  ACID.      TEMP.      15" 


C3H4 
02per 
cent. 

Specific 
gravity. 

C2H4 
02per 
cent. 

Specific 
gravity. 

C2H4 
02per 
cent. 

Specific 
gravity. 

C2H4 
02  per 
cent. 

Specific 
gravity. 

0... 

1.0000 

26.. 

1.0363 

51.. 

1.0623 

76.. 

1.0747 

1... 

1.0007 

27.. 

1.0375 

52.. 

1.0631 

77.. 

1.0748 

2... 

1.0022 

28.. 

1.0388 

53.. 

1.0638 

78.. 

1.0748 

3... 

1.0037 

29.. 

1.0400 

54.. 

1.0646 

79.. 

1.0748 

4... 

1.0052 

30.. 

1.0412 

55.. 

1.0653 

80.. 

1.0748 

5... 

1.0067 

31.. 

1.0424 

58.. 

1.0660 

81.. 

1.0747 

6... 

1.0083 

32.. 

1.0436 

57.. 

1.0666 

82.. 

1.0746 

7... 

1.0098 

33.. 

1.0447 

58.. 

1.0673 

83.. 

1.0744 

8... 

1.0113 

34.. 

1.0459 

59.. 

1.0679 

84.. 

1.0742 

9... 

1.0127 

35.. 

1.0470 

60.. 

1.0685 

85-. 

1.0739 

10... 

1.0142 

36.. 

1.0481 

61.. 

1.0691 

86   . 

1.0736 

11... 

1.0157 

37.. 

1.0492 

62.. 

1.0697 

87  . 

1.0731 

12... 

1.0171 

38.. 

1.0502 

63.. 

1.0702 

88.. 

1.0726 

13... 

1.0185 

39.. 

1.0513 

64.. 

1.0707 

89.. 

1.0720 

14... 

1.0201 

40.. 

1.0523 

65.. 

1.0712 

90.. 

1.0713 

15... 

1.0214 

41.. 

1.0533 

66.. 

1.0717 

91.. 

1.0705 

16... 

1.0228 

42.. 

1.0543 

67.. 

1.0721 

92.. 

1.0696 

17... 

1.0242 

43.. 

1.0552 

68.. 

1.0725 

93.. 

1.0686 

18... 

1.0256 

44.. 

1.0562 

69.. 

1.0729 

94.. 

1.0674 

19... 

1.0270 

45.. 

1.0571 

70.  . 

1.0733 

95.. 

1.0660 

20... 

1.0284 

46.. 

1.0580 

71.. 

1.0737 

96.. 

1.0641 

21  .. 

1.0298 

47.. 

1.0589 

72.. 

1.0740 

97.. 

1.0625 

22... 

1.0311 

48.. 

1.0598 

73.. 

1.0742 

98.. 

1.0604 

23... 

1.0324 

49.. 

1.0607 

74.. 

1.0744 

99.. 

1.0580 

24... 

1.0337 

50.. 

1.0615 

75.. 

1.0746 

100.. 

1.0553 

25. . . 

1.0350 

TABLE    SHOWING     THE     PERCENTAGE     OF    AMMONIA     (NHs)     CONTAINED     IN 
SOLUTIONS  OF  DIFFERENT  SPECIFIC  GRAVITIES.      TEMP.,    14°   (CARIUS). 


Am- 

Am- 

Am- 

Am- 

Specific 

monia, 

Specific 

monia, 

Specific 

monia, 

Specific 

monia, 

gravity. 

per 

gravity. 

per 

gravity. 

per 

gravity. 

per 

cent.     | 

cent. 

cent. 

cent. 

0.8844 

36 

0.9052 

27 

0.9314 

18 

0.9631 

9 

0.8864 

35     ' 

0.9078 

26 

0.9347 

17 

;     0.9670 

8 

0.8885 

34 

1    0.9106 

25 

0.9380 

16 

0.9709 

7 

0.8907 

33 

0.9133 

24 

0.9414 

15 

0.9749 

6 

0.8929 

32 

0.9162 

23 

0.9449 

14 

0.9790 

5 

0.8953 

31 

0.9191 

22 

0.9484 

13 

0.9831 

4 

0.8976 

30    ! 

0.9221 

21 

0.9520 

12 

!     0.9873 

3 

0.9001 

29     ! 

0.9251 

20 

0.9556 

11 

0.9915 

2 

0.902<? 

28     , 

0.9283 

19 

0.9593 

10 

0.9959 

1 

270 


TABLES. 


TABLE    SHOWING     THE  AMOUNT  OF  KaO     IN    POTASS  A    LYE     OF    DIFFERENT 
SPECIFIC  GRAVITIES.      TEMP.,    17.5°. 


Hoffman,  Schaedler,  "Tabellen  fur  Chemiker  "  p. 

119. 

K20 

K20 

K20 

K20 

per 

Specific 

per 

Specific 

per 

Specific 

per 

Specific 

cent. 

gravity. 

cent. 

gravitj . 

cent. 

gravity. 

cent. 
12. 

gravity. 

45. 

1.576 

34. 

1.414 

23. 

1.209 

1.135 

44.5 

1.568 

33.5 

1.407 

22.5 

1.263 

11.5 

1.129 

44. 

1.560 

33. 

1.400 

22. 

1.257     ' 

11. 

1.123 

43.5 

1.553 

32.5 

1.393 

21.5 

1.250 

10.5 

1.117 

43. 

1.545 

32. 

1.886 

21. 

1.244    : 

10. 

1.111 

42.5 

1.537 

31.5 

1.879 

20.5 

1.238     i 

9.5 

1.105 

42. 

1.530 

31. 

1.372 

20. 

1.231 

9. 

1.099 

41.5 

1.522 

30.5 

1.365 

19.5 

1.225     1 

8.5 

1.094 

41. 

1.514 

30. 

1.358 

19. 

1.219     | 

8. 

1.088 

40.5 

1.507 

29.5 

1.852 

18.5 

1.213 

7.5 

1.082 

40. 

1.500 

29. 

1.345 

18. 

1.207     | 

7. 

1.076 

39.5 

1.492 

28.5 

1.339 

17.5 

1.201 

6.5 

1.070 

39. 

1.484 

28. 

1.332 

17. 

1.195     1 

6. 

1.065 

38.5 

1.477 

27.5 

1.326 

16.5 

1.189 

5.5 

1.059 

38. 

1.470 

27. 

1.320 

16. 

1.183 

5. 

1.054 

37.5 

1.463 

26.5 

1.313 

15.5 

1.177 

4.5 

1.048 

37. 

1.456 

26. 

1.307 

15. 

1.171 

4. 

1.042 

36.5 

1.449 

25.5 

1.301 

14.5 

1.165 

3.5 

1.037 

36. 

1.442 

25. 

1.294 

14. 

1.159 

3. 

1.031 

35.5 

1.435 

24.5 

1.288 

13.5 

1.153 

2.5 

1.026 

35. 

1.428 

24. 

1.282 

13. 

1.147 

2. 

1.021 

34.5 

1.421 

23.5 

1.275 

12.5 

1.141     J 

1.5 

1.015 

TABLE   SHOWING   THE  SODIUM  OXIDE  (Na20)  IN    SODA  LYES   OF    DIFFERENT 
SPECIFIC  GRAVITIES.      TEMP.,    17.5°. 


Hoffman-Schaedler,  "Tabellen  fur  Chemiker." 


Na20 
per 
cent. 


Na20 

Na20 

per 

Specific    | 

per 

Specific 

cent. 

gravity.     ; 

cent. 

gravity. 

i 

35. 

1.500 

27.5 

1.389 

34.5 

1.492 

27. 

1.382 

34. 

1.485 

26.5 

1.375 

33.5 

1.477 

26. 

1.367 

33. 

1.470 

25.5 

1.360 

32.5 

1.463 

25. 

1.353 

32. 

1.455 

24.5 

1.345 

31.5 

1.448 

24. 

1.338 

31. 

1.440 

23.5 

1.331 

30.5 

1.433 

23. 

1.324 

30. 

1.426 

22.5 

1.317 

29.5 

1.418 

22. 

1.309 

29. 

1.411 

21.5 

1.302 

28.5 

1.404 

31. 

1.295 

28. 

1.396 

20.5 

1.288 

20. 

19.5 

19. 

18.5 

18. 

17.5 

17. 

16.5 

16. 

15.5 

15. 

14.5 

14. 

13.5 

13. 


Na20 

Specific 

per 

gravity. 

cenv. 

1.281 

12.5 

1.274 

12. 

1.2  6 

11.5 

1.259 

11. 

1.252 

10.5 

1.245 

10. 

1.238 

9.5 

1.231 

9. 

1.224 

8.5 

1.217 

8. 

1.210 

7.5 

1.203 

7. 

1.195 

6.5 

1.188 

6. 

1.181 

5.5 

Specific 
gravity. 


1.174 
1.167 
1.160 
1.153 
1.146 
1.139 
1.132 
1.125 
1.118 
1.111 
1.104 
1.097 
1.090 
1.083 
1.076 


TABLES. 


271 


TABLE  OF  SPECIFIC   GRAVITY   OF  SOLUTIONS  OF  SODIUM  CHLORIDE  AT   15° 
WATER  AT  15°  =  1. 


Gerlach,  "Specifische  Gewichte  der  Salzlosungen. 


Per  cent. 

Specific  gravity. 

Per  cent. 

Specific  gravity. 

1 

1.00725 
1.01450 
1.02174 
1.02899 
1.03624 
1.04366 
1.05108 
1.05851 
1.06593 
1.07335 
1.08097 
1.08859 
1.09622 

I   14 

1.10384 

2 

15 

1.11146 

3 

16 

1.11938 

4 

17 

1.12730 

5 

18 

1.13523 

6 

19 

1.14315 

7 

20 

1.15107 

8 

21 

1.15931 

9 

22 

1.16755 

10 

23 

1.17580 

11 

24 

1.18404 

12 . 

25 

1.19228 

13.. 

26 

1.20098 

TABLE  SHOWING  THE  PERCENTAGE  OF  AMMONIUM  CHLORIDE  IN  SOLUTIONS 
OF  DIFFERENT  SPECIFIC  GRAVITIES.      TEMP.,    15°.      WATER  AT   15°  =  1„ 

Gerlach,  "Specifische  Gewichte  der  Salzlosungen." 


Per  cent. 

Specific  gravity. 

Per  cent. 

t 

Specific  gravity. 

1 ,o 

2 Q0 

1.00316 
1.00632 
1.00948 
1.01264 
1.01580 
1.01880 
1.02180 
1.02481 
1.02781 
1.03081 
1.03370 
1.0365S 
1.0394? 

: 

14 

15 

1.04325 
1.04524 

3 

16 

1.04805 

4 0 

17 

1.05086 

5 

18 

1.05367 

6 

19 

1.05648 

7 

20 

1.05929 

8. 

21 

1.06204 

9 

22 

1.06479 

10 

23 

24 .. 

25 

1.06754 

11 

1.07029 

12 

1.07304 

13 

26 

1.07375 

INDEX. 


Page. 
Absorption,  Determination    of   Carbonic 

Acid  by 24,    25 

Absorption,  Determination  of  Water  by . .    38 

Acetic  Acid  (Reagent) 33 

in  Lime  Acetate 221 

Strength  of  (Table) 269 

Acetate  of  Lime,  Analysis 221 

Acidimetry  and  Alkalimetry 207 

Albumen  in  Flour 255 

Albuminoid  Ammonia 179, 180 

Albuminoids  in  Flour 248 

Alkalies.     (See  also    Potassium,  Sodium, 
Ammonium. ) 

Alkalies  in  Bone-Black ?. 236 

in  Clay 68 

"       in  Feldspar 53 

in  Iron  Ore 97 

in  Limestone 66 

inSlag 101 

"       in  Superphosphate 202 

Uncombined  in  Soap 252 

in  Water 176 

Alkalimetry  and  Acidimetry 207 

Alkaline  Metals  in  Cast-Iron,  etc 118 

Alum,  Ammonia  Iron  (Anal.) 40 

Potassium  (Analysis) 26 

Alumina  (Determination) 26 

InClay 67 

"         in  Feldspar 52 

"         in  Iron  Ore 93,    94 

*•         etc.,  in  Mineral  Water 185 

•'         in  Paint 170 

•'         inSlag 101 

"         in  Water 174 

Alumina  and  Ferric  Oxide  in  Limestone ...    60 
"  "  "  in     Manganese 

Ore 70 

Aluminum  in  Cast-Iron,  etc 117 

Ammonia,  Free  and  Albuminoid 179, 180 

in  Iron  Ammonia  Alum 47 

in  Gas 251 

in  Guano 223 

in  Superphosphate 202 

Iron  Alum  (Sulphate )  ( Anal. ). . . .    40 
Ammonium  Carbonate  (Reagent)  11.27,  32,  144 
Copper  Sulphate,  Kiefer's  So- 
lution      75 

Chloride  (Reagent) 53 

Strength  of  (Table). .  271 

"  Hydrate  (Reagent) 11,    26 

Strength  of  (Table). .  269 
u  Magnesium  Phosphate 17 


Page. 

Ammonium  Oxalate  (Reagent) 11,   21 

Phospho  Molybdate 81,    83 

"  Solution  (Water  Analysis) . . .  179 

Anhydride,  Phosphoric.    (See  Phosphoric 
Acid.) 
Sulphuric.       (See       Sulphuric 
Acid.; 

Antimony  in  Cast-iron,  etc 118 

in  Copper  Ore 137 

in  Refined  Lead 158  et  seq. 

in  Type  Metal 154 

•     "  Ore  (Analysis) 152 

"  Tetroxide  (Sb304) 153 

Apothecaries'  Weight 262 

Apparatus  for  Carbonic  Acid  Determina- 
tion  22,    25 

Argentic.    (See  also  Silver.) 

Nitrate  (Reagent) 11,    14 

Arsenic  in  Cast  Iron,  etc 118 

"       in  Copper  Ore 137 

"       in  Iron  Ore 97 

in  Refined  Lead 158  et  seq. 

in  Type  Metal 154 

Ore  (Analysis) 149 

Arsenious  Acid  Solution  (Volumetric) 218 

Ash.    (See  also  Mineral  Matter.) 

in  Flour 256 

in  Milk 205 

in  Raw  Sugar 229 

in  Superphosphates 202 

Atomic  Weights  (Table) 263 

Available  Chlorine 219 

"  Oxygen 72 

Avoirdupois  Weight 262 

B 

Barium  Carbonate  in  Paint 168 

"        Chloride  (Analysis) 12 

"         (Reagent) 18 

inBaCla 12 

in  Cast-iron,  etc 102 

in  Limestone 64 

in  Mineral  Water 189 

"       Sulphate  in  Paint 168 

Sulphate  (Precipitate) 12,    18 

Barytes  in  Paint 169 

Beakers 8 

Beaume  and  Specific  Gravity  (Tables). 264,  265 

Bismuth  in  Refined  Lead 160  et  seq. 

Bleaching  Powder 219  et  seq. 

Bone-Black  Analysis 234 

Boracic  Acid  in  Mineral  Water 190 

Bromide,  Potassium  (Anal.) 35 


274 


]T^DEX. 


Page. 

Bromine  (Determination) 35 

in  Mineral  Water 191 

"         Water  (Reagent) ?I 

Bronze  (Analysis) 147 

Burner,  Standard 246 

Burning  Point  of  Oil 244 

•«        Oil  in  Petroleum 243 

Butter  in  Milk 204 

c 

Cadmium  in  Refined  Lead 160  et  seq. 

Calcium.    (See  also  Lime.) 

"  in  Calcium  Carbonate 31 

"  in  Cast-iron,  etc 117 

Carbonate  (Analysis) 21 

(Reagent) 53 

Chloride  (Reagent) 32,  39 

Chloride  Solution  "Hardness".  177 

"  Fluoride  (Analysis). 31 

Oxalate  (Precipitate) 21 

Sulphate  (Precipitate) 21 

"  Sulphate  in  Paint 168, 170 

Calculation  Acetate  of  Lime  222 

"  Bicarbonate  of  Soda 216 

"  Bleaching  Powder 219 

"  Manganese  Oxides "76 

"  Mineral  Waters 193 

Water  Analysis  182 

Candle,  Standard 246 

Carbon  Combined,  in  Cast-Iron,  etc 108 

"        Colorimetric 108 

Dioxide.    (See  Carbonic  Acid.) 

Fixed.inCoal 238 

inSugar 231 

in  Turpentine 233 

"        Total,  in  Cast-iron,  etc 104 

Carbonate  Ammonium  (Reagent) — 11, 27,    32 

"  Calcium,  Analysis 21 

"         (Reagent) 53 

Barium,  in  Paint 168 

"  Basic  Lead  in  Paint 170 

"  in  Manganese  Ore 73 

"  Sodium  (crude) 212 

"  "       (Reagent) 32 

"  "       Bi- (Analysis) 215 

"  "in  Alkalimetry 207 

"  "       in  Mineral  Water 185 

in  Soap 253 

"  "       Solution,  Water  Anal. .  179 

Carbonic  Acid  by  Direct  Weight 24 

"     by  Loss 22 

"in  Bicarbonate  of  Soda 215 

"     in  Bone-Black. 234 

"     in  Iron  Ore 97 

"     in  Limestone  62 

"     in  Mineral  Water 187 

Casein  in  Milk 205 

Cast-Iron  (Analysis) 102 

Cellulose  in  Flour 256 

Chlorhydric  Acid.    (See  Hydrochloric  Acid.) 

Chloride  Ammonium  (Reagent) 53 

"         Barium  (Analysis) 12 


Page. 

Chloride  Barium  (Reagent) 18 

Calcium  (Reagent) 32,  39 

"       Solution,  "Hardness"...  177 

Potassium  Platino 28,    30 

Silver,  Precipitate 14 

Sodium 37 

"      Strength  of  (Table) 271 

Chlorimetry 218- 

Chlorine  Available 219 

' '  Effect  on  Permanganate 48- 

inBaCl2 • 13 

in  Bicarbonate  of  Soda 216- 

in  Bone-Black 236 

"  in  Iron  Ore 97 

"  in  Limestone 65 

"         in  Mineral  Water 187 

"'         in  Soap 254 

in  Superphosphate 201 

"         in  Water 175 

"         Water  (Reagent) 35 

"         Volumetric  Determination. .  .175,  218 
Chromate,  Bi-,  Potassium,  Volumetric  So- 
lution.     46 

Chromium  in  Cast-Iron,  etc 117 

"  in  Iron  Ore 89 

Citric  Acid,  Strength  of  (Table) 268 

Clay,  Analysis  Grav. ,  and  Mechanical 67 

"     in  Paint 168 

Coal  Analysis 238 

Cobalt  and  Nickel,  Electrolytic  Det 131 

"  "        Separation...  128  etseq.,  134 

in  Cast-Lron,  etc 117 

"       in  Iron  Ore 96 

"       in  Refined  Lead 159  et  seq. 

Cochineal  Indicator. 211 

Combined  Carbon  In  Cast-Iron,  etc.  (Color- 
imetric)  108 

Combustible,  Volatile,  in  Coal 238 

Completeness   of  Burning  and  Washing 

Bone-Black 237 

Copper- Ammonium  Sulphate  (Kiefer's  So- 
lution)     75 

Copper,  Determination  as  Cu2S 133 

CuO 138 

Electrolytic  Determination 136 

Potassium  Tartrate 228 

in  Bronze 147 

"       in  Cast-Iron,  etc 118 

in  German  Silver 140 

inlronOre 97 

in  Refined  Lead 160  et  seq. 

"       OreAnalysis 136 

Coralline  Indicator 211 

Crucibles & 

Cubic  Foot.  Weight  of,  Bone-Black 23*5 

D 

Decolorizing  Power  of  BoneBlacic 237 

Delivery  Mark  of  Flasks 4 

Distillation,  Fractional 242 

Distilled  Water,  Water  Analysis 180 

Dittmar's  Flux 85 


INDEX. 


275 


Page. 

Electrolytic  Det.  of  Cobalt  and  Nickel.  ...  131 

Copper 136 

Elementary  Analysis  of  Sugar 231 

"  Turpentine 233 

F 

Fat  in  Milk 204 

"    in  Flour 256 

"    Uncombined  in  Soap 253 

Fatty  Acids  in  Soap 252 

Feldspar  Analysis 49 

Ferric  Compounds.    (See  Iron.) 

Ferric  Ammonio  Sulpliate  (Anal.) 40 

Ferrous  Compounds.    (See  Iron.) 
Ferrocyanide  Potassium,  Volumetric  Solu- 
tion  125 

Filtering 8 

Filter  for  Carbon  in  Iron  and  Steel 105 

Papers  in  Flour  Analysis 257 

Fineness  of  Bone-Black 236 

Fixed  Carbon  in  Coal 238 

Flashing  Point  of  Oil 244 

Flasks,  Measuring,  Standardizing 3 

Flour  Analysis 255 

Fluoride,  Calcium  (.Analysis) 31 

ofSilicon 31 

Potass '  um  Silico 32 

Fluorine  (Determination) 31,    32 

in  Iron  Ore 97 

"         in  Limestone 66 

Formula  for  Sp.  Gr.  and  Degrees  Be 264 

Fractional  Distillation 242 

Free  and  Albuminoid  Ammonia 179, 180 

French  and  United   States   Weights    and 

Measures  (Tables) 262 

Fusion 49,    85 

"       Dittmar's  Flux 85 

Hart's  Method 79,    95 

"       Smith's  Method 53 

G 

Galena  Analysis 142 

Gallon,  U.  S 174, 183 

Gas,  Illuminating,  Examination 245 

"    Ammonia  in 251 

"    Photometry 245 

"    Specific  Gravity 245 

"    Sulphur  in 249 

German  Silver  Analysis 140 

Glucose,  Artificial,  in  Raw  Sugar 230 

in  Raw  Sugar 223 

Glycerine  in  Soap C54 

Grains  in  Gallon,  Mgs.  in  Litre 1S3 

Graphite  in  Cast-Iron,  etc 112 

Guano  Analysis 223 

Gum  in  Flour 255 

H 

"  Hardness  "  of  Water 176 

'               "Permanent"  and  "Tempo- 
rary"  178 

Heating  Power  of  CoaL 240 


Page. 

Holding  Mark  of  Flasks 3 

Hydrate,  Ammonium  (Reagent) 11,  26 

Strength  of  (Table). .  269 

Potassium  (Normal) 208 

"  "         or    Sodium,  Strength 

of  (Table) 270 

Hydrochloric  Acid 34 

"               "     for  Decomposing  Man- 
ganese Ore 75 

"     Normal 211 

"     Strength  of  (Table) 266 

Hydro-Disodium  Phosphate  (Analysis) 36 

(Reagent) 18 

Hydrogen  in  Sugar 231 

in  Turpentine    233 

Hydrometer  Beaume  Deg.  (Tables) 264 

I 

Ignition 9 

Illuminating  Gas 245 

Indicators,  Alkalimetry,  etc 210 

Introduction 1 

Inverting  Sugar  227 

Iodide  Palladium 34 

"       Potassium  (Analysis) 34 

Iodine  (Determination) 34 

in  Mineral  Water 191 

Iodized  Starch  Paper 218 

Iron  Ammonia  Alum  (Sulphate)  (Anal.) 40 

"    Cast  and  Wrought  ( Analysis) 1 02 

"    and  Alumina  in  Limestone 6<> 

"    and  Alumina  in  Manganese  Ore 70 

"    and      Alumina,      etc.,      in      Mineral 

Water 185, 189 

"    by  Ignition 41 

"    by  Precipitation 40 

' '    by  Volumetric  Determination 41,    46 

"    inBone-Black 236 

•'    in  Bronze 148 

"    in  Cast-iron,  etc 102 

"    in  Clay 67 

"    in  Feldspar 52 

"    in  German  Silver 141 

"    in  Iron  Ammonia  Alum 41 

"    inlronOre 79,    84 

"    in  Refined  Lead 159  et  seq. 

"    in  Slag 101 

"    in  Tin  Ore 146 

"    in  Type  Metal 154,  156 

"    in  Water  174 

' '    Method  for  Available  Oxygen 73 

"  "       for  Bleaching  Powder 220 

"    Ore,  Complete  Analysis 86 

"    Containing  neither  Titanium  nor 

Chromi   m 98 

"       "    Containing    Titanium     and     no 

Chromium 98 

"       "    Partial  Analysis 78 

)'    Volumetric  Determination 41,    46 

Wire Stt    43 


276 


INDJCX. 


Page. 

K 

Kiefers  Solution 75 

Kroonig  Valve 42 

L 

Lead  Carbonate  Basic  in  Paint 170 

Lead  in  Bronze 117 

in  Galena 143 

in  Type  Metal 154 

Oxide  in  Paint 172 

Refined  (Analysis) 157 

Sulphate  in  Paint 168, 170 

Letheby  Sulphur  Apparatus 249 

Lime  Acetate  (Analysis) 221 

in  Clay 67 

in  Feldspar B3 

in  Iron  Ore 95 

in  Limestone 80 

etc.,  in  Mineral  Water 185 

in  Slag 101 

in  Water 174 

Soda-  (Reagent) 24 

Lime,  Superphosphate  (Analysis) 197 

Limestone  Analysis 59 

Linear  Measures 262 

Lithium  in  Feldspar 57 

in  Mineral  Water 190 

Litmus  Indicator 211 

Litre,  Milligms.  in,  Grains  in  Gallon 183 

Logwood  Indicator 211 

M 

Magnesia  Determination 17 

In  Cast-iron,  etc 117 

in  Clay 67 

in  Feldspar 53 

In  Iron  Ore 95 

in  Limestone 61 

in  Mineral  Water 185 

in  Blag 102 

in  Water 174 

Mixture 11,    37 

Magnesium  Ammonium  Phosphate 17 

Magnesium  Pyro- Arsenate,  Purifying 150 

"  Pyrophosphate 17,    38 

Sulphate  Analysis 17 

Mtinganate  Per-,  Volumetric  Solution 41 

Manganese  in  Cast-iron,  etc 117 

"  in  Clay 68 

"  in  Limestone 64 

"  in  Iron  Ore 94 

in  Slag 101 

in  Mineral  Water 189 

in  Refined  Lead 159  et  seq. 

"  Ore  Analysis 70 

Oxides,  Calculating 76 

Silicate 72 

Marguerite's  Volumetric  Determination  of 

Iron 41 

Measures  and  Weights,  United  States  and 

French  (Tables) 262 

Measuring 2 


Page. 

Mercuric  Oxide  (Reagent) 128 

Mercurous,  Nitrate  tReagent) 126 

Meter,  Gas 247 

Milk  Analysis 204 

"     Standard. . 206 

Milligrammes  in  Litre  and  Grains  in  Gal- 
lon  183 

Mineral  Matter.    (See  also  Ash.) 

"         in  Guano 225 

inMilk 205 

inSoap 254 

Mineral  Water  Analysis 184 

Moisture.    (See  Water.) 

Molybdate  Phospho  Ammonium 81,  83 

Molybdate  Solution 11 

Molybdenum  in  Cast-Iron,  etc 120 

N 

Naphtha  In  Petroleum 243 

Nessler's  Solution 179 

Nickel  and  Cobalt,  Electrolytic  Determi- 
nation  131,135 

Nickel  and  Cobalt,  Separation 128,  134 

"       in  Cast-iron,  etc 117 

in  German  Silver 140 

in  Iron  Ore 96 

in  Refined  Lead 159  et  aeq. 

Ore  Analysis .  127 

Nitrate  Argentic  (Reagent)- II,    14 

"       Mercurous  (Reagent) 128 

Silver  Volumetric  Solution 175 

Nitrates  in  Water 181 

NitricAcid 85 

"in  Mineral  Water 191 

"    Strength  of  (Table) ....267 

Nitrate  Potassium  (Reagent) 129 

Nitrogen  in  Bone-Black 236 

"         In  Cast-iron,  etc 119 

Normal  and  Half  Normal  Solutions 207 

Note  Books 9 

Notes  on  Coal 239 

o 

Oil,  Burning,  in  Petroleum 243 

"    Flashing  and  Burning  Point 244 

"    in  Paint 168 

Oils,  Parafflne,  in  Petroleum 243 

Organic  and  Volatile  Matter  in  Water 173 

"        Matter  in  Feldspar 57 

"       in  Iron  Ore 97 

"  "       in  Limestone 63 

Oxalate  Ammonium  (Reagent) 11,    21 

Calcium  21 

"        Potassium  (Reagent) 72 

Oxalic  Acid,  Half  Normal 212 

"         "     (Reagent) 43 

Oxide  Di-,  Carbon.    (See  Carbonic  Acid.) 

"      Mercuric  (Reagent) 128 

"       Manganese  Calculation 76 

"       Titanic,  in  Iron  Ore 91 

Oxygen  Available 72 

"  "         Iron  Method 73 

"  "         Pattinson's  Method 74 


INDEX. 


277 


Page. 

P 

Paint  Analysis 167 

Palladium  Chlor  de  (Reagent) 34,  192 

Palladium  Iodide 34 

Palladium,  Metalli  j 34 

ParaffineOils  in  Petroleum 243 

Permanganate  Potassium  (Reagent) 42 

"  "  test  on  Water, 

178, 180 

Petroleum  Analysis  242 

Phosphate  Hydro-Disodium  (Analysis) 86 

"  "  "         (Reagent) 17 

"         Magnesium  Ammonium 17 

"  "  Pyro-(Reagent)....17,38 

Phospho  Molybdate  Ammonium 81,  83 

Phosphoric  Acid  in  Bone-Black 234 

"     in  Guano 223 

"             "     in  Hydro-Disodium  Phos- 
phate     37 

«'  "     inlronOre 80,93 

"  "     in  Limestone 62 

"  "     in  Magnesium    Pyro-Arse- 

nate 150 

"     in  Mineral  Water 189 

"  "     inSlag 101 

"             "     (Insoluble)  in  Superphos- 
phate  199 

"              "     (Precipitated)   in    Super- 
phosphate  199 

"             •'     (Soluble)    in     Superphos- 
phate  198 

"     Volumetric  Det 200 

"  Anhydride.      (See  Phosphoric 

Acid.) 

Phosphorus  in  Cast-iron,  etc 114 

Photometer,  etc 247 

Pipettes,  Graduating,  etc 4 

Platino  Chloride,  Potassium 28,  30 

PlatinumFoil 45 

"(Spongy) 29 

M  "   Tetrachloride  Reagent 11,  28 

Plumbic  Compounds .    (See  Lead . ) 

Polarizing  Sugar  226 

Porosity  of  Bone-Black 237 

Potable  Water  Analysis 173 

Potassium.    (See  also  Alkalies.) 

"  Alum  (Analysis) 26 

"  Bromide  (Analysis) 35 

Bichromate  Volumetric  Solu- 
tion      46 

"  Copper  Tartrate    228 

(Determination) 27,  30 

"            Ferrocyanide  Volumetric  So- 
lution  125 

Hydrate  (Normal)    208 

"  "        Strength  of  (Table)..  270 

in  Feldspar 53 

"  in  Mineral  Water 186 

"  in  Water 176 

••  Iodide  (Analysis) 34 

H  Nitrate  (Reagent) 129 


Page. 

Potassium  Oxalate  (Reagent) 72 

"  Permanganate  (Reagent) 42 

"  "  Test  on  Water, 

178,  180 

Silico  Fluoride 32 

Bisulphate 87 

Power,  Heating,  of  Coal 240 

Pressure  in  Gas  Testing 248 

Q 

Quartz  Sand  in  Clay 6* 

R 

Raw  Sugar  (Analysis) 226 

Reagents,  Excessive  use  of 1 

MakingUp 10 

"        Valueoflc.  c 11 

Referee's  Sulphur  Apparatus  249 

Report  on  Coal 239 

"      on  Guano •  • .  225 

"      on  Petroleum 243 

"      on  Superphosphate 203 

Resin  in  Soap       253 

Rochelle  Salt  (Reagent) 228- 

s 

Saccharimeter 226 

Sal  Ammoniac 53 

Salts     (See  also  Ash  and  Mineral  Matter.) 

SaltsinMilk 205 

Saratoga  Waters,  Analysis  of 194 

Scheibler's  C02  Apparatus 234 

Silica  31,32 

"    inClay 57 

"    in  Feldspar 51 

•'    inlronOre 79,88 

"    in  Limestone 60 

"    in  Mineral  Water 185 

"    in  Paint.  .  168 

"    in  Slag 101 

"    in  Tin  Ore 146 

"    in  Water 174 

Silicates  in  Clay 68 

Silico  Fluoride  Potassium 32 

Silicon  Fluoride..  31 

in  Cast-iron,  etc 102, 114 

Silver  Chloride  (Precipitate) 14 

"     in  Galena 143, 144 

'•     in  Refined  Lead 157 

•'     Nitrate  (Reagent) 11,    14 

"         "       Volumetric  Solution 1 75 

Slag  Analysis 100 

"     in  Cast-Iron,  etc 121 

Smith,  J .  L . ,  Method  of  Det .  Alkalies 53 

Soap  Analysis 252 

Solution  for  "  Hardness  " 177 

Solids,  Total  in  Mineral  Water 184 

Solvents 2 

Soda  Ash  (Analysis),  Alkalimetry.  .  212 

"        Bicarbonate  Analysis 215 

Soda  Lime  (Reagent) 24 

Sodium  Carbonate  (Crude) 212 

"  "  (Reagent) 32 


278 


INDEX. 


Page. 

Sodium  Cai  bonate  (Reagent)  in  Alkalimetry  207 

in  Water  Anal.  179 

"  "  in  Mineral  Water 185 

"      Chloride 37 

"       Strength  of  (Table) 271 

Hydrate,  Strength  of  (Table) 270 

"      Hydro-Di-,  Phosphate  (Analysis) 36 

(Reagent)....    17 

"       in  Bicarbonate  of  Soda 216 

"       in  Feldspar 53 

' '      in  Hydro-Disodium  Phosphate 36 

in  Water 176 

Sulphite  (Reagent) 82 

"      Sulpho  Stannate 145 

Specific  Gravity  and  Beaume  (Tables) 264 

"        of  Gas 245 

Starch  in  Flour 256 

"     Paper  Iodized 218 

Standard  in  Milk 206 

Standardizing  Alkalimetric.etc,  Solutions  209 

Flasks  3 

"  Potassium  Permanganate..    42 

Stannate,  Sulpho-Sodium 145 

Stannic  Compounds.    (See  also  Tin.) 

"       Oxlde(Bronze)  147 

Steel  Analysis 102 

Strontium  in  Limestone 64 

"         in  Mineral  Water 189 

Sugar  in  Flour 247 

"      in  Milk 206 

"     Inverted  827 

"      Raw(Analysis) 226 

"     Ultimate  Analysis 231 

Sulphate  Aluminum  Potassium  (Analysis).    26 
"         Ammonio  Copper,  Kief er's  Solu- 
tion     75 

"         Ammonio  Ferric  (Anal.) 40 

Barium 12,  18 

"     in  Paint 168 

Calcium  (Precipitate) 21 

in  Paint 168.170 

"         in  Soap 254 

"         in  Sodium  Bicarbonate 216 

Leadin  Paint 168,170 

"         Magnesium  Analysis 17 

Potassium  Acid  (Reagent) 87 

Sulphite  Sodium  (Reagent). 82 

Sulpho-Stannate,  Sodium 145 

Sulphuric  Acid  (Reagent) 11 

"     Half  Normal 207 

"  "     in  Guano 224 

"      inMgSO*.... 18 

"     in  Mineral  Water 185 

"  "in  Superphosphate  202 

"     in  Water  175 

"     Strength  of  (Table) 265 

"         Anhydrite.    (See  Sulphuric  Acid.) 
Sulphur  Compounds  in  Mineral  Waters.  . .  195 

In  Coal 238 

"       In  Cast-Iron,  etc 114,116 

"        In  Galena 144 


Page. 

Sulphur  in  Gas  249 

in  Iron  Ore 80,    96 

"        in  Limestone 96 

in  Refined  Lead 165 

"        Waters  (Analysis) 194 

Superphosphate  of  Lime  (Analysis) 197 

T 

Table  for  Calculating  Water  Analyses 183 

Table  for  Scheibler's  Apparatus 235 

Tables  of  Weights  and  Measures 258 

Tartaric  Acid,  Strength  of  (Table) 268 

Tin  in  Bronze 147 

"    in  Cast-Iron,  etc 118 

"    in  Refined  Lead. .  158  et  seq. 

"    in  Type  Metal 155 

"    Ore  Analysis 145 

Titanium  in  Cast-Iron, etc 102 

"        inClay 67 

"         inlronOre 85,91,    92 

Titration.    (See  Volumetric.) 

Total  Solids  in  Mineral  Water 184 

TroyWeight 262 

Tungsten  in  Iron  Ores 100 

Turpentine,  Ultimate  Analysis 233 

Type  Metal  Analysis 154 

u 

Ultimate  Analysis  of  Coal 240 

"        of  Sugar 231 

"  "         of  Turpentine 233 

Uranium  Solution,  Volumetric 201 

United   States  and  French   Weights   and 
Measures  (Tables) 262 

V 

Valve,  Kroonig 42 

Vanadium  in  Cast-Iron,  etc 120 

"  in  Iron  Ores 99 

Vinegar  Analysis 213 

Volatile  and  Organic  Matter  in  Water 173 

Combustible  in  Coal 238 

Volumetric  Determination  of  Chlorine 175 

Volumetric  Determination  of  Chlorine  in 

Chlorides 2J8 

Volumetric  Determination  of  Iron 41 

Volumetric  Determination  of  Phosphoric 

Acid 201 

Volumetric  Determination  of  Zinc 125 

Volume  of  Coal,  Weight  of 239 

w 

Water  Chlorine  (Reagent) 35 

Water  Determination,  Direct,  by  Absorp- 
tion     38 

Water  Determination  by  Loss 16, 19,    30 

"      Distilled  for  Water  Analysis 180 

"      Fresh,  or  Potable  Analysis 173 

"       "  Hardness"  of 176 

in  Barium  Chloride,  etc 16, 19,    30 

"       in  Clay 67 

in  Coal 38 

"       in  Feldspar 57 

"       in  Flour. 267 


INDEX. 


279 


Page. 

Water  in  Guano 224 

"      in  Iron  Ore 97 

"       in  Limestone 63 

"       in  Milk 204 

in  Raw  Suear  229 

"       in  Soap 254 

"       in  Sodium  Bicarbonate 215,216 

"       in  Superphosphate  of  Lime 202 

"       Mineral  (Analysis) 184 

Waters,  Saratoga 194 

Sulphur 194 

Washing 8 

Weighing 5 

Weights  and  Measures,  United  States  and 
French  (Tables) 254 


Page. 

Welter's  Law 241 

Witherite  in  Paint  168 

Wrought-Iron  Analysis 102 


Zinc,  Amalgamated  45 

"      in  Bronze 148 

"      in  Cast-Iron,  etc 117 

"      in  German  Silver    140 

"      in  Iron  Ore 96 

"      in  Nickel  Ores 134 

in  Refined  Lead 159  et  seq. 

"      Oxide  in  Paint 170 

"      OreAnalysis 123 

"     Volumetric  Determination 125 


1 


